When you lack evidence it’s ok to say “I don’t know”. It’s expected of people who do science. Cosmologists have for decades been doing mathematics, not science.

There is a theory that the big bang was not a one time phenomena and has happened more than once Therefore there can be multiverses

I only believe in things I see evidence of. This hypothesis is unproven, so I can’t say I believe it. However, is it a possibility? Perhaps is the answer to that question.

I don’t know enough to have a legitimate opinion, but the idea seems preposterous. The sheer number of splits is mind boggling.

Perhaps all those other universes exist only as virtual possibilities but ours is the one being watched by universal consciousness.

Belief is a personal emotion of little significance.

In order to have a (any) "belief", I look for actual evidence. So far, all I have read about is ideas (hypotheses) that, from a physics perspective, they could exist and may provide explanations for some phenomena.