My dad used to live in Gulfport, and we shot at one place near some railroad tracks I believe in Biloxi (in the old part but within seeing distance of the casinos I think). I wished I could remember the name for you, but this was 10 years ago or more. It had about 30 tables in there or more. It was a nice place then but not sure about now. I'm sure there are plenty down there now or you would think. Sorry I couldnt help more.
You can also try to search Google maps for "billiards" or "Pool hall", etc. and it might bring something up.