Is a paper more likely to be accepted if one of the authors is an associate editor for the journal?
In principle, no.

In actuality? It likely does, under a couple of different mechanisms:


An editor might be slightly more likely to give your paper the "benefit of the doubt" if its a borderline case between Revise/Reject, etc. This may also be true if your co-authors are "known" names, regardless of their editorial position.
An AE at a journal likely has extensive experience writing for, and reviewing, papers in that journal. As such, they probably have a good sense what kind of papers they're looking for, the tone they should be written in, etc.


So the answer, in a practical sense, is likely "Yes, but not by a huge amount." And possibly not after controlling for recognition and experience.