Would wild gorillas do well in South America, amazon, rainforest?

Hard to know for sure but its possible that western lowland gorillas from e.g. Congo are might do OK in parts of the Amazon if they became established after an initial translocation. However, leaving aside the fact that we wouldn't actually want to put the Amazonian ecosystem at risk by adding a non-native animal like that, sucesful translocation of wild animals is often unsuccesful. Think of e.g. the stress of capture, transport and release, followed by a requirement for a pretty steep learning curve of what plants were edible/nutritious/poisonous, what predators were dangerous etc etc. If you get past those then other problems could arise, e.g. perhaps some pathogens could host jump from new world monkeys into the gorilla population who would lack resistance etc etc.

So  - in principle - yes they migh do well eventually. In practice getting them established would probably be difficult even if it were deemed desirable.