It's a confusing issue, and I say this as a Louisiana resident who has asked the question, and has looked at the law. I've been a cop for thirty years, and I'm not sure if it's legal.
Further confusing the issue is that we have several types of casinos in Louisiana, and they all fall under different legislative authorities. We've got the little truck-stop casinos, we've got riverboat casinos, we've got Indian casinos.
So, the better question is; which casino are you talking about? It really gets down to that.
Further confusing the issue is that just last year we passed an amendment to our state constitution that identifies firearm possession as a fundamental right, subject to strict scrutiny in the courts. The courts aren't really sure what they're going to do with the laws currently on the books, but when we raised the legal scrutiny to "strict", we opened a huge can of worms.
I don't carry in a casino, and it's one of very few places that I don't carry. A fairly good explanation of
Louisiana law can be found here, and it's written in non-lawyer English. There are still gray areas, and casinos are one of them.