Cuma akşamı tiyatroya gideceğim, çünkü biletleri çoktan aldım.

Cuma akşamı means Friday evening / on Friday evening.

The -ı here is not the accusative case. It is the suffix commonly used in a noun compound, where one noun modifies another:

• Cuma akşamı = Friday evening
• Pazartesi sabahı = Monday morning
• yaz tatili = summer vacation

So this is a very common way Turkish forms time expressions with days and parts of the day.

Because gitmek usually takes the dative case when you are going to somewhere.

• tiyatro = theater
• tiyatroya = to the theater

The dative ending is -(y)e / -(y)a. Since tiyatro ends in a vowel, Turkish adds a buffer y:

• tiyatro + a → tiyatroya

Similar examples:

• okula gidiyorum = I’m going to school
• eve gidiyorum = I’m going home
• Ankara’ya gidiyorum = I’m going to Ankara

This is because gitmek has a common stem change in some forms:

• git- → gid-

So:

• gitmek = to go
• gidecek = he/she will go
• gidiyorum = I am going

Then the full form is built like this:

• gid-ecek-im → gideceğim

Also, the k in -ecek softens to ğ before the personal ending.

So gideceğim means I will go.

A useful learner-friendly approximation is:

gi-de-JE-im or gi-de-JE-yim

A few pronunciation points:

• c in Turkish sounds like English j in jam
• ğ is not a hard g
• in a word like gideceğim, ğ often acts like a glide or lengthens the vowel slightly

So don’t pronounce it like a strong English g.

Because biletleri is a definite/specific direct object.

In Turkish, a specific direct object usually takes the accusative ending.

• biletler = tickets
• biletleri = the tickets

So:

• Bilet aldım = I bought a ticket / I bought tickets
• Biletleri aldım = I bought the tickets

In this sentence, the speaker means specific tickets that have already been bought.

Yes, it can, depending on context.

biletleri can mean either:

• the tickets
  or
• his/her tickets

This happens because the form can represent different grammatical structures. In this sentence, the meaning is clearly the tickets, because of the context:

• ... çünkü biletleri çoktan aldım = ... because I already bought the tickets

So even though the form is technically ambiguous, the sentence makes the intended meaning clear.

Yes, almak can mean to take, to get, or to buy, depending on context.

With things like tickets, bread, clothes, and similar items, almak very often means to buy:

• ekmek aldım = I bought bread
• bilet aldım = I bought a ticket / tickets

Turkish also has satın almak, which more explicitly means to purchase, but almak is very natural and common in everyday speech.

çoktan means something like:

• already
• long ago
• well before now

It emphasizes that the action was completed earlier than the present moment, often with the sense that it was done in good time.

So:

• biletleri çoktan aldım = I already bought the tickets
• with a nuance like I bought them some time ago / I’ve had them for a while already

çünkü means because and is commonly used to add an explanation after the main statement:

• Cuma akşamı tiyatroya gideceğim, çünkü biletleri çoktan aldım.

This is very natural.

If you want to put the reason first, Turkish often prefers a different structure, such as -dığı için:

• Biletleri çoktan aldığım için cuma akşamı tiyatroya gideceğim.
• Because I already bought the tickets, I’ll go to the theater Friday evening.

So yes, the reason can come first, but usually not with çünkü in the same way English uses because.

Not completely. Turkish word order is flexible, but the verb usually comes at the end.

This sentence follows a very normal pattern:

• Cuma akşamı = time
• tiyatroya = destination
• gideceğim = verb
• çünkü... = explanation

You can move parts around for emphasis, but some versions sound more neutral than others. For example:

• Cuma akşamı tiyatroya gideceğim. = very neutral
• Tiyatroya cuma akşamı gideceğim. = emphasizes to the theater
• Biletleri çoktan aldım, o yüzden cuma akşamı tiyatroya gideceğim. = another natural way to express the idea

In this sentence, Cuma is capitalized because it is the first word of the sentence.

Normally, days of the week in Turkish are not capitalized unless they begin a sentence:

• Bugün cuma.
• Cuma akşamı tiyatroya gideceğim.

So the capital letter here is because of sentence position, not because weekdays are always written like proper nouns in English.

Not in this sentence if you mean go to the theater.

• tiyatroya = to the theater → direction/destination
• tiyatroda = in/at the theater → location

Since gitmek here expresses movement toward a place, Turkish uses the dative:

• tiyatroya gitmek = to go to the theater

If you were describing where you are, then tiyatroda would be correct:

• Şu anda tiyatrodayım. = I’m at the theater now.