Rules and policies will determine if it is possible or not.
This is normal rule in casinos since for sure that they don't want to deal with their people since it will create a controversy especially if they win huge amount. We can't deny that there are people will create any bad stories against the casino and will say that only their employee is winning in that places that's why maybe this one contribute to the factor on why casino didn't allow their workers to gamble in their casino.
Also rules maybe different to other casino but usually that is what I see on the casino I go. But also I don't think the worker might also like to gamble anymore since they are dealing with gambling activities whole day and for sure they want separation of their job to their private life so provably that majority of casino workers will just take a rest and prepare their selves to work on next day.