The answer for the question varies - if the person only cares about money - then surely - the staff will be fired
But if the casino would care for people as well - they would consider the situation as well. But gambling is a merciless game. You don't care for people. You only care for money.
It does not need to fire the staff, a suspension is enough if it is the staff's first offense. Personal matter should not be brought in work. Besides, the staff does not need to shout to the person (his relative), he can just ask for the assistance of guards to throw the person out of the casino or best to consult the manager in charge on dealing with his addicted relative.
The staff could've shouted at his addicted relative after days of patience and expressing his opinion in a polite way. Even we will lose patience after certain trials of trying to make a person get out of addiction and take care of his family. If I were the manager, surely I'll call for an enquiry. If I wasn't satisfied with the reason from the staff I'll give warning, and won't think of firing. Because, the entire family might've got dependence over his earning for life.