"Subscribe to Pewdiepie" became a bit of a meme/running joke last year when Pewdiepie's 60-odd million subscribers were telling everyone else to subscribe to him so he wouldn't be overtaken by YouTube's second biggest channel. People would spam tweet it, or sign off videos with it.
He has had a few run ins that far-right people might notice - he's said the N word a few times on camera, he (supposedly unknowingly) recommended another channel run by a white supremacist and has been accused of making anti-semitic jokes.
Decent write up here -
https://www.vox.com/2018/12/13/1813...-links-to-white-supremacist-alt-right-redpill
I think it's just a case of the right attaching themselves to a figure who they think is on their side, while Pewdiepie is really just a bit of a shock-jockey who occasionally oversteps the mark. He's not actively pushing far right material or really politically inclined at all as far as I'm aware, not that I'm a regular viewer.