Hi! If you're here, it's possibly because I referred you to this page because you're interested in creating an article for a YouTube personality. While this page is oriented towards YouTubers, especially those in the Let's Play community, it can be used to cover the general topic of people who are notable for their actions on any given social media outlet since the majority use the same general guidelines to establish prominence (fanbase numbers, view counts, etc). I'm not going to go too much into general sourcing and notability, as you can read a guideline here that contains basic information about sourcing.
Popularity
One of the most common arguments for notability for YouTubers or YT videos is that they have large fan followings or view counts. Unfortunately popularity doesn't count towards notability on Wikipedia. It makes it more likely that there will be coverage, but it's not a guarantee. Some of my favorite YouTubers (Simply Nailogical, KPOPP, Pushing Up Roses) have a decently sized amount of fans and views, yet they've not gained the type of coverage necessary to pass notability guidelines. Part of the reason that subscribers count does not count towards notability is because it's actually not difficult to purchase subscriber numbers. While it's unlikely that someone with millions of subscribers will have purchased all of them, it has happened enough in the past that Wikipedia just can't use that as a sign of notability. A somewhat similar example as to why we can't use social media followings as a sign of notability on its own without coverage in RS would be Robert Stanek. In his case, part of his claim to fame was that his work had received hundreds of reviews on Amazon and other websites. It eventually came out that the vast majority of these reviews were either written by Stanek himself or were ones he'd paid others to write. The same thing kind of goes for subscriber/fan counts, as there have been instances of people artificially creating their follower counts.
Another reason popularity doesn't count towards notability is that this sort of thing is kind of subjective. A person can get attention, however sometimes people get attention for things that just aren't all that notable as far as the overall span of Internet history goes and sometimes can be a bit of a flash in the pan. I've also heard some say that it's becoming common enough for people to gain followings on social media and YouTube, so this isn't considered to be the sign of notability that it once was. It's kind of a tricky thing to really explain overall, but the main thing to remember is that you can't judge notability by follower numbers.
Coverage and establishing notability
The sad fact is that most social media personalities will not gain the type of coverage necessary to pass notability guidelines. There might be multiple reasons for this, not all of which are fair, but Wikipedia needs to have coverage in independent and reliable sources like articles in newspapers or trusted websites in order to establish notability. Even then you have to be careful, since a burst of coverage in a very short period of time might not always be enough, as coverage for one specific video or incident could be seen as WP:ONEEVENT. If the article topic is about a minor (typically seen as anyone under the age of 18) then that coverage will have to be especially in-depth and heavy to justify an article, given how protective Wikipedia can be about younger people.
Past cases
When it comes to establishing how difficult it is to pass notability guidelines I always like to hold up PewDiePie as an example. Pewds is incredibly popular, however his article kept getting deleted until June 2013, only months before he became the most subscribed channel on YouTube. Considering that he was seen as the face of Let's Play prior to that, it's probably mind boggling for many to imagine that his article was deleted at AfD back in 2012, with an almost unanimous consensus. Another example of difficulty is Dan Avidan, whose article went up for deletion in June 2016. Avidan is a member of two notable musical groups (Ninja Sex Party, Starbomb) and one of the presenters of Game Grumps, a popular series with over 3 million subscribers. A bunch of us had to really fight to establish notability for Avidan at the last minute, as there were many people arguing against his notability - and even then it ended up that what gave him notability were the bands, as they had albums that charted and received reviews. It's just that difficult to establish notability.
Epilogue
So does this mean that you shouldn't try to create an article? Not necessarily. Just because it's difficult to establish notability and unlikely that there will be coverage doesn't mean that the person or video doesn't deserve an article. My best recommendation is to create an article at AfC and submit it through that process, because you'll have the ability to work on the article at your leisure without fear of immediate deletion, which can happen if you post something directly to the mainspace.
