On the side of the employer, it all depends on how much they are able to steal from the casino, There are denominations set by some companies that would determine whether they deserve to be laid off without any felonies or misdemeanors in their name, or if they really need to get jailed lol. For some it's as little as a 100 bucks, for some there may not even be any type of denomination and you'll automatically be carried to court if you're caught on the act. So don't bother stealing something from your company, the money that you took from them won't be worth shit to how much they can charge you back when you get put into court for the crime, and you also run the risk of doing the time itself, and getting a hit on your name which won't be good for employment. Don't be stupid, stay on the right and narrow and do not risk your life getting ruined over a couple hundred or thousands of dollars.
In this case, it depends on the company policies regarding misuse of funds, no matter where they used it. Because some companies are indeed strict when it comes to implementation of their policies especially if the funds involved is big. But for small companies, and the amount is not significant, they may settle it with the employee like being laid off and paying what he owed to the company.
If the gambling addict still continue to work even if he knows he has gambling problem, then, I would say, he is indeed looking for a chance to get money from the casino coffers and use it. The casino will determine if it is misdemeanor (petty theft) or a felony (grand theft) and punish the person accordingly.