The answer: NO. This is one of the things that sets Disney off from the cruise industry standard. The entire cruise line is focused more on the family than anything else. This shows in their children's programs, which, if I recall correctly was one of the 'extras' they had room to include by cutting out (a) casino(s) (BTW... the movie theatre is another). Disney wanted to keep that family oriented feeling throughout the ship... hence the slashing of the casino.
But, for those who really want casinos on their trip, in Nassau, you can take a short trip to Atlantis. While in Freeport, I know that there are some. And for those on a seven night cruise, I'm almost certain St. Thomas and/or St. Maarten, as well as Cozumel all have a casino of their own.
Hope this helps you... By all means, don't let this be the decision maker in whether or not you choose Disney Cruise Line... The ship has other features that the entire family will enjoy instead of just a certain group of the family... If it's just you or just a couple, take advantage of the adult only areas, such as Beat Street, etc. and Quiet Cove Pool. Another tip, whether it be just you, a couple or a family: check out Deck 7 Aft. The deck on the back of the ship is the largest public deck, and it makes for a great place to watch the land fade away, almost always by yourself.