Misafirler gitti mi mutfağı birlikte toplarız.

Not here. In this sentence, -mi is not making the whole sentence into a real question.

After a verb, -DI mi can mean when/once/after in a very natural Turkish way.

So:

• Misafirler gitti mi... = When the guests have left... / Once the guests leave...

This is a very common pattern in Turkish:

• Eve vardın mı beni ara. = Once you arrive home, call me.
• Yemek bitti mi çıkarız. = When the meal is over, we leave.

So even though mi often marks yes/no questions, in this structure it works more like a time marker.

Because mi is a separate particle in Turkish, not a normal suffix that attaches directly to the word.

That is why you write:

• gitti mi
• geldin mi
• hazır mı

not as one word.

It still follows vowel harmony in its form:

• mı, mi, mu, mü

In your sentence, gitti mi uses mi because of vowel harmony.

Turkish often uses a singular verb form with a plural subject, especially when the plural subject is already clearly stated.

So:

• Misafirler gitti = perfectly normal
• Misafirler gittiler = also possible, but often a bit more marked or explicit

Since misafirler already means the guests, the plural is already clear. Turkish does not always need plural marking again on the verb the way English does.

This is especially common in everyday speech and neutral statements.

Toplarız is the aorist form, and in a sentence like this it often expresses a general rule, usual practice, or natural next step.

So:

• Misafirler gitti mi mutfağı birlikte toplarız.

means something like:

• Once the guests leave, we tidy up the kitchen together
• When the guests have gone, we clean up the kitchen together

It sounds like a normal pattern or what we do in that situation.

If you said:

• Misafirler gitti mi mutfağı birlikte toplayacağız

that would sound more like a specific future plan for one occasion.

So toplarız is not just simple present here; it often works like we will in this kind of time-based sentence.

Literally, toplamak means to gather / collect, but in many everyday expressions it means to tidy up / clean up / put in order.

So:

• odayı toplamak = tidy the room
• masayı toplamak = clear the table
• mutfağı toplamak = tidy/clean up the kitchen

In this sentence, mutfağı birlikte toplarız means we tidy up the kitchen together or we clean up the kitchen together.

Because it has the definite accusative ending, since it is the direct object of toplarız.

Base noun:

• mutfak = kitchen

As a definite object:

• mutfağı = the kitchen

Two things happen:

1. The accusative ending is added: -(y)ı / -(y)i / -(y)u / -(y)ü
2. The final k changes to ğ in this form

So:

• mutfak → mutfağı

This is very common in Turkish:

• kitap → kitabı
• çocuk → çocuğu
• renk → rengi

It usually means when/once the guests leave, not a doubtful if.

The structure verb + -DI mi normally suggests that the speaker sees the event as expected or as the point after which something happens.

So the feeling is:

• Once that happens, then we do this

If you wanted a more clearly conditional if, Turkish often uses -se/-sa:

• Misafirler giderse mutfağı birlikte toplarız.

That is closer to:

• If the guests leave, we tidy up the kitchen together

But your original sentence sounds more like:

• When the guests have left, we tidy up together

Birlikte means together.

Here it modifies the verb:

• mutfağı birlikte toplarız = we tidy up the kitchen together

Its position is fairly flexible in Turkish. You could also hear:

• Misafirler gitti mi birlikte mutfağı toplarız.
• Misafirler gitti mi mutfağı toplarız birlikte.

But the original order sounds very natural.

Turkish word order is flexible, but speakers choose positions to make the sentence sound smooth or to emphasize different parts.

Yes. The ending -ız shows that the subject is we.

So:

• toplarım = I tidy up
• toplarsın = you tidy up
• toplarız = we tidy up

Because Turkish verbs carry person marking, the separate pronoun biz is not necessary unless you want emphasis.

So:

• Mutfağı birlikte toplarız already means We tidy up the kitchen together

Yes:

• Misafirler = the guests
• gitti = went / left
• mi = here, when/once
• mutfağı = the kitchen (as a definite object)
• birlikte = together
• toplarız = we tidy up / we clean up

A natural overall sense is:

• Once the guests leave, we tidy up the kitchen together.

A comma is often possible in writing, especially to separate the time clause from the main clause:

• Misafirler gitti mi, mutfağı birlikte toplarız.

But Turkish punctuation is not always as strict as English in this kind of structure, and many people write it without a comma too:

• Misafirler gitti mi mutfağı birlikte toplarız.

Both are commonly seen.