Gorillas are pretty tough and can beat most any other animal.
However a bear is much stronger than a gorilla and if a gorilla comes up against a bear and gets into a fight with the bear then the bear is most likely to win the fight.
There have been bears and gorillas fighting and in all those videos I've seen the bear has won the fight against the gorilla.
Most gorillas would try to get around or away from the bear because it likely knows that they cannot win the fight against the bear.
A bear is stronger than a gorilla or monkey or most any other animal.
A bear could easily kill a gorilla or a monkey if they got into a fight.