As powerful as gorillas are....they are herbivores too.
The argument that vegans constantly make about large, strong animals being vegetarian is invalid. Firstly, the reason they are so large is because they are vegetarian. Gorillas spend virtually all of their time feeding because the food they eat is such poor quality and low in nutrients. So do elephants, rhinos, buffalos etc. Vegetarian animals are large at a cost to themselves. They require huge stomach and intestine volume to digest their food and they must constantly eat. Because they are so big and heavy, they require a lot of muscle and bone strength to constantly move and feed. And because they are at risk from predators and usually live together in a hierarchical group structure they need to be able to defend themselves and compete for food, mates, space etc. hence the strength of male gorillas, antlers of deer, horns of rhinos etc.
Compare this to a pure carnivore, who can afford to lie around all day, feed once in a while yet are extremely muscular and strong, far stronger than herbivores on a pound for pound basis.