All mechanical devices can fail. Let's just say that due to their simplicity, revolvers are much less likely to fail mechanically. Ironically, most revolver failures are, like many semi-auto failures, caused by ammunition. More irony: Such revolver failures are more likely to render the pistol (Yes, a revolver is still a pistol) inoperative until repair can be made.
Simple ammunition failure, such as a dud round, is easily solved: pull the trigger again.
The ammunition caused failures that can render one inoperable are: squib load lodging in the barrel, overloaded round causing rounds to bind against recoil plate or causing primer to back out and do the same. I had one cause a firing pin to break once.
True mechanical failures are less common, but one I see frequently is the ejector rod unscrewing itself under recoil and binding the cylinder upon attempting to open. Most of the rest come from gross neglect, and are very rare. A revolver can sit in a sock drawer for 50 years, be pulled out and do what it needs to.
To answer the question, yes; revolvers are more reliable than semi-autos. Some good candidates are: S&W J-frames, pick your style there. (442), Ruger LCR, Ruger SP101, Charter Arms (A plus with these is they are available in semi-auto rounds), Colts, though not made any more and becoming more expensive due to collectors, are still excellent guns. (DS, Agent, Cobra, Python, Police Positive, Trooper, Lawman, etc.)