What's for sure is that Shakespeare raises the issue in the play and reflects questions that were on the minds of thinkers in his day. Predestination vs. free will was an issue in Shakespeare's time, as, in fact, it still is today. Shakespeare's play reflects this. The issue may be seen as a refinement or continuation of the question of fate, which goes back at least as far as the Greeks.
The fact is that in the play the issue is ambiguous, and an argument can be made supporting that Macbeth was controlled by fate, or that Macbeth maintained free will.