No, I've never heard of any credible evidence that he survived. First-hand testimony from residents of the Fuhrerbunker attest to his final moments.

Beyond that, Hitler's suicide was not outside of his behaviorally pattern. After the failure of his attempted Putsch in 1924, his first impulse was to kill himself after he fled the scene. Unfortunately for a great many people, he was convinced not to. So. Hitler was most definitely a self-destructive fatalist, and it would have been quite atypical of him to try to escape and live out his days in hiding/obscurity. Rumors of his survival are popular among conspiracy theorists. In a parallel case, Deputy Fuhrer Martin Bormann disappeared in the last days of the war and was tried in absentia at Nuremberg. His skeletal remains were found by construction workers in Berlin in the 1970s and were confirmed to be his by DNA analysis in the 1990s, yet there are people who claim he survived and escaped to some other country. Some people will just believe what they want to, evidence be damned.

As to the second part of your question, yes there were. The most famous case is that of SS doctor Josef Mengele, who performed grotesque medical "experiments" on prisoners at Auschwitz. By the time Nazi hunters tracked him down and got the local authorities to agree to pursue him, he had already died in the Brazilian jungle. This was not uncommon for "lower level" Nazis who could blend into the fabric of postwar society, though usually outside of Europe.