All four gorilla subspecies are currently on the Red List. Only about 300 Cross River gorillas, 720 Mountain gorillas and at most 5000 Eastern lowland gorillas roam the jungle. The main threat factors are poaching and habitat destruction. There are also increasing signs that the dangerous Ebola virus is eradicating entire stocks of gorillas. Only the western lowland gorilla population with about 90,000 animals seems to be sufficiently large.
source: WWF