Is everything pre-determined in OOTS world?

[Dion]

You are the one grossly mistaken and indeed clearly ignoring the evidence in front of you. The Oracle is not doing guesswork. He has been shown capable of predicting the times of his own death down to the exact minute. That is far, far beyond guesswork.

Knowing the exact count of words that would give V ultimate Arcane power is a similar example of something beyond guesswork. As is Haley's answer, and of course Elan's.

I never said the oracle was guessing. I said there's no reason to believe he knows more than he's saying.

Yes, the oracle knew the exact count of words. That doesn't mean he knew which words, or who V would say them to, or why, or when, or anything else beyond the fact that their would be 4 words.

Think about it like math. There are all sorts of theorems in math that tell you that an object must satisfy some factual statement, without telling you how it satisfies that statement. For example, the fundamental theorem of arithmetic is "every natural number can be factored into unique primes". But just because you can look at an number and say unequivocally that it factors into unique primes, that doesn't give anyone the ability to actually know what the primes are.

My default position for any story with accurate prophecy is that the story occurs in a universe where a prophecy is a mathematically true statement (like there are unique prime factors), without necessarily telling you how it's true (like what the prime factors actually are).

The Oracle clearly knows some things in very great detail. But his knowledge of the world is similar to V's ability to throw fireballs. Just because V can throw a fireball, that doesn't make V omnipotent. And just because the oracle can know some things, that doesn't make the oracle omniscient.