There is nowhere to hide in South America if the CIA is after you. Russia, or China, or Muslim countries would be better. Venezuela is US's backyard. He would have to be on guard 24/7/365, but the extraction force would only need to get one favorable occasion. As an extreme measure, they will just send a word that his head would be well paid for. I do not see how he can survive, short of a major surgery and fake ID.
If I were Snowden I’d take a job at the Starbuck’s in Odenton, Maryland where lots of the NSA people get their coffee every morning. The last thing they’d ever notice is the barista making their vente latte for them.