Quanto mais amaciante você coloca, mais forte fica o cheiro da roupa.

It means the more..., the more....

So:

• Quanto mais amaciante você coloca... = The more fabric softener you put in...
• ...mais forte fica o cheiro da roupa. = ...the stronger the smell of the clothes gets.

This is a very common Portuguese structure for showing a correlation between two things.

Other examples:

• Quanto mais você estuda, mais aprende.
  = The more you study, the more you learn.
• Quanto mais cedo sairmos, melhor.
  = The earlier we leave, the better.

Because quanto mais... mais... is a fixed comparative pattern in Portuguese.

It works like this:

• quanto mais X, mais Y
• quanto menos X, menos Y
• quanto mais X, menos Y
• quanto menos X, mais Y

Examples:

• Quanto mais ele come, mais fome sente.
• Quanto menos você dorme, mais cansado fica.

So quanto is not optional here in standard usage. It helps create the full the more... structure.

Amaciante means fabric softener.

It comes from the verb amaciar, which means to soften.

So:

• amaciar = to soften
• amaciante = softener / fabric softener

In everyday Brazilian Portuguese, amaciante usually refers specifically to laundry softener unless the context suggests something else.

Because the sentence is expressing a general truth or usual result, not something happening only once.

Portuguese often uses the present tense for this, just like English does:

• The more you add, the stronger it gets.
• Quanto mais você coloca, mais forte fica.

So você coloca here means something like:

• you put in
• you add
• you use

in a general, habitual sense.

In this sentence, keeping você is the most natural choice.

You may hear subject pronouns omitted in Portuguese, but with você there is an important detail:

• você takes third-person singular verb forms
• so coloca could also mean he/she puts

Because of that, leaving out você can create ambiguity.

So these are better:

• Quanto mais amaciante você coloca, mais forte fica o cheiro da roupa.
• Quanto mais amaciante a gente coloca, mais forte fica o cheiro da roupa.

Without the pronoun, it may sound less clear.

Here fica means becomes or gets.

The verb ficar has several meanings in Portuguese, and one very common one is to become / to get:

• ficar triste = to become sad
• ficar pronto = to become ready / to be ready
• ficar mais forte = to get stronger

So:

• mais forte fica o cheiro da roupa
  = the smell of the clothes gets stronger

It does not mean stays in this sentence.

Both are possible.

The more neutral word order is:

• o cheiro da roupa fica mais forte

But in the sentence you gave, Portuguese places mais forte earlier for emphasis and rhythm:

• mais forte fica o cheiro da roupa

This kind of word order is very natural, especially in comparative or more expressive sentences.

So these are both acceptable:

• Quanto mais amaciante você coloca, mais forte fica o cheiro da roupa.
• Quanto mais amaciante você coloca, o cheiro da roupa fica mais forte.

The original version sounds a little more elegant or emphatic.

Because da is a contraction of de + a:

• de + a = da

So:

• o cheiro da roupa = the smell of the clothes / the smell of the laundry

Using the article a with roupa is natural here. In Brazilian Portuguese, roupa can work collectively, meaning clothes or laundry in general.

Compare:

• cheiro da roupa = the smell of the clothes/laundry
• cheiro de roupa = smell of clothing / clothing smell

The version with da roupa sounds more specific and natural in this sentence.

Cheiro is usually neutral. It just means smell.

Depending on context, it can be good, bad, or neither.

Examples:

• cheiro bom = good smell
• cheiro ruim = bad smell
• mau cheiro = bad odor
• fedor = stink

In your sentence, mais forte fica o cheiro da roupa just means the smell becomes stronger. It does not automatically say whether that is good or bad, although in context it may suggest the scent is too strong.

Yes. Pôr and colocar can both work here.

So you could say:

• Quanto mais amaciante você coloca...
• Quanto mais amaciante você põe...

Both mean something like the more fabric softener you put in.

A small nuance:

• colocar is often a bit more neutral and widely used
• pôr is also very common in speech

In everyday Brazilian Portuguese, both are perfectly normal.

Forte is very natural when talking about smells.

• cheiro forte = strong smell
• perfume forte = strong perfume

You could say intenso, but it sounds a bit more formal or descriptive:

• cheiro intenso = intense smell

So in everyday speech, forte is the more common choice.

Also note the difference between:

• mais forte = stronger
• melhor = better
• mais agradável = more pleasant

A stronger smell is not necessarily a better smell.

In Brazilian Portuguese, amaciante is pronounced approximately like:

• a-ma-ci-AN-te

The stress falls on AN.

A rough English-friendly guide:

• ah-mah-see-AHN-chee or ah-mah-see-AHN-tee

The exact final sound depends a bit on accent, but the important part is the stress on -an-.

A few other useful pronunciations from the sentence:

• quanto → roughly KWAN-too
• você → voh-SEH
• cheiro → roughly SHAY-roo
• roupa → roughly HOH-pah with a guttural Brazilian r

It sounds like a general observation, and depending on context it can also sound like a warning.

By using the present tense, Portuguese gives it a broad, general meaning:

• Whenever you add more fabric softener, the smell gets stronger.

If someone says this while discussing laundry, it may imply:

• Don’t overdo it
• More fabric softener isn’t always better

So grammatically it is a general statement, but pragmatically it can easily function as advice or a warning.