Repliklerini hatırladığın sürece suflöre ihtiyacın yok.

Repliklerini means your lines in this sentence.

It breaks down like this:

• replik = line, spoken line, reply
• -ler = plural
• -in = your
• -i = accusative marker

So:

• replikler = lines
• repliklerin = your lines
• repliklerini = your lines as the direct object of the verb

Turkish often packs a lot of information into suffixes, so one word can correspond to several English words.

Because it is a specific direct object.

The verb hatırlamak means to remember, and here the speaker is talking about a definite set of lines: your lines. In Turkish, definite/specific direct objects usually take the accusative.

So:

• repliklerini hatırlamak = to remember your lines
• the -i at the end marks that object as specific

This is very common in Turkish. English does not mark this difference on the noun, but Turkish does.

This is a very common Turkish pattern.

• hatırla- = remember
• -dık = a clause-forming suffix
• -ın = marks the subject as you
• sürece = as long as / so long as

So hatırladığın sürece means something like:

• for as long as you remember
• more naturally: as long as you remember

A useful pattern to remember is:

• Verb + -DIK + possessive + sürece = as long as someone does...

For example:

• geldiğin sürece = as long as you come / as long as you keep coming
• bildiğim sürece = as far as I know / as long as I know

Because of a sound change.

The underlying form is based on -dık, but when another vowel-initial suffix follows, the final k often softens to ğ.

So the rough development is:

• hatırla + dık + ın
• becomes hatırladığın

This kind of softening is very common in Turkish and is something you will see a lot.

You could say hatırlarsan, but it gives a slightly different meaning.

• hatırlarsan = if you remember
• hatırladığın sürece = as long as you remember

So:

• if you remember sounds like a single condition
• as long as you remember emphasizes that the situation remains true during that whole time

In this sentence, hatırladığın sürece is the better choice because it matches the idea: you do not need a prompter for the whole time that you still remember your lines.

Because ihtiyaç normally takes the dative case for the thing needed.

So Turkish says:

• bir şeye ihtiyacı olmak = to have need of something
• bir şeye ihtiyaç duymak = to need something

That is why you get:

• suflör = prompter
• suflöre = to/for a prompter

So suflöre ihtiyacın yok means you have no need for a prompter.

Literally, it means your need does not exist.

Breakdown:

• ihtiyaç = need
• -ın = your
• yok = absent, nonexistent, there is not

So:

• ihtiyacın yok = you have no need / you do not need

This is a very natural Turkish way to express not needing something.

A more verbal version would be:

• Suflöre ihtiyaç duymuyorsun. = You do not need a prompter.

Both are correct, but suflöre ihtiyacın yok sounds very natural here.

Because yok and değil do different jobs.

• yok = something is absent / does not exist
• değil = is not, used to negate identity or description

Here the idea is there is no need, so yok is the correct choice.

Compare:

• Doktor değil. = He/she is not a doctor.
• Doktor yok. = There is no doctor.

So:

• ihtiyacın yok = your need is absent
• ihtiyacın değil would not work here

It is talking to one person.

You can see that from the endings:

• hatırladığın = you remember with singular you
• ihtiyacın = your need with singular you

If you wanted to say it to more than one person, or use polite you, it would be:

• Repliklerinizi hatırladığınız sürece suflöre ihtiyacınız yok.

So the original sentence uses singular you.

Yes, it is very normal.

Turkish often puts the condition or time clause first, and the main statement after it:

• Repliklerini hatırladığın sürece = as long as you remember your lines
• suflöre ihtiyacın yok = you do not need a prompter

That order sounds natural and clear in Turkish.

You could move things around for emphasis, but this version is the most neutral and natural one.