I'm Catalan, and the correct pronunciation is LIE-uh or LAH-yuh, I'm not sure how to explain it. But it isn't Lay-a, that's for sure. I'd use
Leia for this pronunciation.
I love
Laia, but a bit too popular -here- for my taste.
Leia is also lovely, and
Leah too. They're all awesome names!
Good luck!