I'm also Iranian!It's definitely true that if you're a white young male, you generally have a slightly higher chance of making it "big" on YouTube. Simply due to the large percentage of YouTube viewers who fall into the under 15 female category!
But apart from that, I don't think being ethnic makes much of a difference. I'm a UK-based YouTuber (but from a Middle-Eastern background) and have never felt that my ethnicity has stopped my channel from growing or anything.
By the way, thanks for mentioning FaresHtv - I'm part Iranian and don't know ANY Iranian YouTubers, so will check his channel out!
Glad to see another one here 
I would say that yes, sex/race/ethnicity (basically any social/cultural concept) DEFINITELY play a role. They play a big role outside of the internet, it's not that surprising that the same cultural biases/underlying racism/sexism/etc., follow that onto the online world. (Possibly at a grander scale, given the power of anonymity.) I can't say how much, as I've done little research on that specific topic. (Not to say I haven't had any personal experiences, haha.) I'm mostly speaking from reading on those who have, seen it in action, and making some logical assumptions. It's a shame though :/