Question

Is Macbeth a tragedy of fate or of character? In determining your position on this, consider whether the witches play a central or collateral role in shifting the ambitions and actions of the play’s characters.

Answer 1

It might be a tragedy of fate after all. Yes, I do think that the witches play a central role in the play, because if it hadn't been for them, none of the tragedy would have happened. If they hadn't told Macbeth about what was to happen, he would never have thought about killing Duncan and becoming king himself. He would have been satisfied with where he was at that particular moment, and proud of himself. This way, the witches destroyed everything by planting the seed of greed in Macbeth, and thus it had to end tragically.  ~THE BRAINLIEST ANSWER!
WorldlyGlass49  Genius

This isn't mine but it should help.

Answer 2

. Macbeth's demise was due to fate (he couldn't control his demise, since it was his destiny)or due to his choices (he earned his demise by being selfish, cruel, scheming, etc). You can argue for either one - I would choose character and say that at every point Macbeth chooses to do something bad, he receives some sort of sign telling him to turn back, but he ignores it. The witches egg him on and tell him that he will be destined to rule over Scotland, etc. I think they play a collateral role; you cannot blame them for Macbeth's sins, but they certainly did help push him down his path
Everything that happens is "fate" not due to their own flaws. Let's say Macbeth goes a little overboard and becomes insanely power-hungry (which he does  you'd still have to say it's because it was his fate. The witches are a good example
since they pretty much decide his fate, unfortunately 
hope it helps