I don't think anything is preying upon gorillas, the biggest predators for chimps are chimps and humans, though young ones are taken by birds too

Humans in the wild are prey to crocodile, big cats, bears, wolves and young ones from an even longer list

Humans and chimpanzees are definitely predators. Humans who lived through the recent ice age outside the tropics were pure carnivores as no edible plants grow on glaciers; all the big animals and most of the dangerous ones went extinct just after humans got to an area

Bonobos eat fruit. Not much eats them

The apes are all pretty good at defending themselves and are their own worst enemy