His support numbers are certainly somewhat pushed up.

However, on Reddit (on the subreddit r/newiran, which I must note is disproportionately pro-Pahlavi) someone proposed a method of verifying how much of his support genuinely came from Iran.

They measured the drop in viewership of his videos at the beginning of the Internet blackout. They concluded that most viewers were from Iran, since traffic dropped several times with the blackout.