It depends on whether the humans coordinate. If it comes down to it, they could all just crowd and suffocate it.
Someone will have to bite the bullet and lead a frontal charge against the gorilla. But realistically, how many out of a hundred untrained, average individuals have the balls to attempt something like that?
If there are any objects on the ground that can be used as weapons (rocks, poles, or sticks) the outcome could very well change drastically, as humans have historically relied on tools (particularly crafted weapons) + teamwork to overcome animals much stronger and larger than themselves.
Cavemen hunted animals much larger and stronger than themselves such as mammoths using spears and coordinated strategies (including ambushes), but without such tools at their disposal, I'd imagine these cavemen would have mostly evolved as vegetarians and scavengers.