No more than the supermarket parking lot or any other business parking lot where you self park your car.
As I am not licensed in your state, I cannot offer specific legal advice as to Mississippi state law. However, generally, hotels and other businesses have been found liable for assaults and robberies against people, based on inadequate security. However, those cases are often difficult and expensive to prove and usually only warrant the expenditure of the needed costs because there has been significant damage to a person. I would doubt that it would be economically feasible to pursue such a claim for a mere property loss. Hopefully you have homeowners insurance which will cover some of the stolen items and coverage on your vehicle which will pay for that damage as well. You also could contact the casino and see whether or not they would be willing to make some reimbursement to you as a good will gesture.
Sign up to receive a 3-part series of useful information and advice about personal injury law.