When a thing turns habitual surely it'll kill time. One such thing had taken place with employee. It is not about gambling, as said whatever he had done apart from his assigned task during the work hours is going to stop his productivity as well as the progress of the firm. This is well understood by the Boss and he had fired the employee.
I said before that this mistake was not caused by gambling but by an employer's playing at the wrong time. The company should have a department that supervises workers and nurtures them if there are problems like this happen again, don't get fired right away before the issue is clear so that the situation can not make a one-sided disadvantage. A problem like this will occur happen on the next time if the company doesn't have a specific rule on how to work in that office because gambling sites around the world have been played very often by workers during working hours.