Im not sure if youre asking should see or will the theater allow her to. The answer to the latter is yes.
The other answer is harder - but you know your child, HER comfort level and your own.
Personally, i feel the answer is she's too young. Rather, MY kids would have been too young.
Its a conversation you need to have with her. What else has she done alone? You dont want to turn what should be a wonderful experience into one she doesnt enjoy due to self doubt.
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.