Does the creator or the audience determine the meaning of a work of art?

Both. We can't perceive the world exactly the same way as another person. Therefore, what we make of it is also individual and every point of view is valid in its own way.

Take a Rorschach-Test, for example. There are examples most people can agree on, they show a specific thing. Others are wildly subjective. What a creator intends to invoke with their creation and what the audience receives are not necessarily the same, but that doesn't invalidate one side's interpretation.