Gdybym miała mniejszy dług, mogłabym wpłacić większą kwotę jeszcze w tym tygodniu.

Yes. This sentence is a standard Polish way to express a hypothetical situation:

• Gdybym miała mniejszy dług = If I had a smaller debt
• mogłabym wpłacić większą kwotę = I could pay in a larger amount

So it works very much like English if I had..., I could.... The idea is that the condition is not true at the moment, so the result is only hypothetical.

Gdybym means if I were / if I had / if I did, depending on the verb that follows. Here it means if I had.

It is built from:

• gdyby = if
• -m = I

So gdybym literally contains the idea of if + I.

In this sentence:

• Gdybym miała... = If I had...

A close alternative would be jeślibym, but gdybym is very natural and common in this kind of hypothetical sentence.

Because the conditional marker is already present in gdybym.

Polish conditional forms use the particle by plus a past-like verb form. But when there is a conjunction like gdyby, the personal ending often attaches to that conjunction instead of to the verb.

So:

• gdybym miała = correct
• gdybym miałabym = incorrect, because that would repeat the conditional marking

Compare:

• Miałabym mniejszy dług = I would have a smaller debt
• Gdybym miała mniejszy dług... = If I had a smaller debt...

In the second version, the -bym has moved onto gdy and become gdybym.

Because the speaker is female.

In Polish, conditional forms are built from a past-like form, and that form shows gender in the singular:

• feminine: miała, mogłabym
• masculine: miał, mógłbym

So this sentence implies a female speaker:

• Gdybym miała mniejszy dług, mogłabym wpłacić większą kwotę...

If the speaker were male, it would be:

• Gdybym miał mniejszy dług, mógłbym wpłacić większą kwotę...

Both phrases are in the accusative case, because they are direct objects:

• mieć dług = to have a debt
• wpłacić kwotę = to pay in an amount / deposit an amount

The difference comes from noun gender and declension.

1. mniejszy dług

dług is a masculine inanimate noun.
For masculine inanimate nouns, the accusative singular usually looks the same as the nominative.

• nominative: mniejszy dług
• accusative: mniejszy dług

2. większą kwotę

kwota is feminine.
Feminine accusative singular changes the endings:

• nominative: większa kwota
• accusative: większą kwotę

So the phrase changes because kwota is feminine, while dług is masculine inanimate.

Wpłacić means to pay in, to deposit, or to make a payment toward something.

In this sentence, it suggests paying a sum into an account or toward a debt. It focuses on the amount being paid in, not necessarily on finishing the debt completely.

Useful contrast:

• wpłacić kwotę = to pay in / deposit an amount
• zapłacić = to pay in a more general sense
• spłacić dług = to pay off a debt completely

So:

• mogłabym wpłacić większą kwotę = I could pay in a larger amount
• mogłabym spłacić dług would mean I could pay off the debt

Here, the speaker is not saying she could eliminate the debt, only that she could make a bigger payment.

Because the sentence refers to one completed payment.

• wpłacić = perfective, one completed act
• wpłacać = imperfective, repeated action or ongoing process

Here the meaning is:

• I could pay in a larger amount (once, as a complete payment)

If you used wpłacać, it would sound more like:

• I could be paying in larger amounts
• I could make larger payments regularly

So wpłacić fits the idea of a single payment sometime before the end of the week.

Here it means something like:

• still this week
• before this week is over
• later this very week

The word jeszcze often adds the idea of still / yet / as early as depending on context. In this sentence, it suggests that the speaker could make that larger payment within the current week, not later.

So the phrase gives a sense of time urgency:

• w tym tygodniu = this week
• jeszcze w tym tygodniu = still this week / already this week before it ends

Yes. You could say:

• Gdybym miała mniejszy dług, to mogłabym wpłacić większą kwotę jeszcze w tym tygodniu.

The to is optional. It often helps mark the result clause, a bit like then in English:

• If I had a smaller debt, then I could pay in a larger amount this week.

Without to, the sentence is still completely natural and correct.

Because Polish usually drops subject pronouns when they are already clear from the verb form.

Here, the first person singular is obvious from:

• gdybym = if I
• mogłabym = I could

So ja is unnecessary unless you want emphasis or contrast.

For example:

• Ja mogłabym wpłacić większą kwotę...
  = I could pay in a larger amount...
  with emphasis on I

Normally, the version without ja sounds more natural.

Yes. Polish word order is flexible, though not completely free. The original sentence is neutral and natural:

• Gdybym miała mniejszy dług, mogłabym wpłacić większą kwotę jeszcze w tym tygodniu.

But you can move elements to change emphasis. For example:

• Jeszcze w tym tygodniu mogłabym wpłacić większą kwotę, gdybym miała mniejszy dług.
  This emphasizes jeszcze w tym tygodniu.

• Większą kwotę mogłabym wpłacić jeszcze w tym tygodniu, gdybym miała mniejszy dług.
  This emphasizes większą kwotę.

So the original version is not the only possible order; it is simply the most straightforward one.

Because Polish commonly uses w plus the locative case for time expressions like in this week / during this week.

So:

• w tym tygodniu = this week / during this week

You will see the same pattern in similar phrases:

• w tym miesiącu = this month
• w tym roku = this year
• w ten weekend is also possible, but weekends often behave a bit differently in usage

Here:

• tym tygodniu is locative after w

That is why the phrase looks the way it does.