I think it works the same way as getting your game on the homepage of itch.io: Luck and popularity. There are plenty of YouTubers who play games on itch.io, you could always reach out to them to see if they'll play your game on their channel

Just having your game published on Itch.io is enough. The admins look at games published here and they post on other social media about games they find that they think could use more attention to it.

There’s no specific official criteria, and that’s by design, so that users focus on making their games better, rather than trying to game the system.