There's one gorilla and 100 men. With 30 men per shift you have enough people to harrass the gorilla with loud noises, feints and just being a potential threat. Don't let it eat, drink or sleep for a few days and it'll likely drop from dehydration if nothing else. Even if it gets water, the average western lowland gorilla needs to eat around 20kg of vegetation per day. I suppose it would depend on where this confrontation took place, but it should be possible to distract it and prevent it eating for some time.
If the contestants, gorilla and human alike, are allowed to pick up and use things in the environment, then it really is game over for the gorilla as it runs from a hail of sticks, stones, mud and anything else the humans can lay their hands on.
A gorilla has a fearsome turn of speed over short distances, but, from what I can find out, even if they slow down close to human walking speed it can only go a few miles before needing to rest. If the humans are allowed use their environment to harrass the gorilla they can kerp it moving long past the point it would choose to stop, and they'll eventually wear it down to the point it can't defend itself.