Keyword Stuffing on Tags and Description

Does keyword stuffing on tags and description on youtube video helps to gain more views?

Confirmed. It won't do any good to your traffic efficiency.

do you have any proof? stats? or something?

This kind of thing just has to be tested to see what works. I've got sets of tags with only 6 words that gets me consistent 2,000+ views /day. I see people in some markets stuff the shit out of their descriptions and tags and get good results. The best thing to do is look at videos that were just put up a day or 2 ago for your keyword and see which ones are doing the best, take the top 5 or so and try it yourself.

cool i might try