According to reports from Harrah's and Boyd gaming, the New Orlean's casinos faired pretty well all things considered. Harrah's reported that their New Orleans casino suffered only "minor damage" and Boyd reported that at least two of their New Orleans area casinos (Boomtown, Bally's) were not heavily damaged. There is still a bit of an known regarding the Treasure Chest, since the extent of the damage wasn't exactly known.

All of the casinos are closed, Harrah's reporting the New Orleans casino would open no earlier than 9/30. I imagine with all of the clean up and infrastructure damage it will be weeks before any of the New Orleans casinos are able to reopen.