In Grand Theft Auto 5, you can only access the casino in the mission “GTA 5 – The Lost and Damned”. It is a small, one-story building that is on the west side of the ruined mall.
You can’t enter it or do anything inside it.
There are several online casinos that allow you to play in real time. Some of the more popular ones are SlotsMillion, Bovada, and Mr Green.
All of these casinos have free trials so you can try out their games before you decide to make a deposit.
