From part of the YouTube FAQ's:
"Q: Do likes, comments, shares, etc. factor into search ranking?
A: We've tested this in the past, however these factors are too easily gamed so they aren't reliable enough to use in ranking. However, the organic ripple effects of these actions may help with discoverability in other ways; for example, if someone "likes" your video, and their 1,000 subscribers see that activity in What to Watch, those 1,000 subscribers may decide to also watch that video."
Source:
https://support.google.com/youtube/answer/6046966