He handled this one really well IMHO. I think this one will just roll right off his back like water off a duck. The mainstream media hates him because he's successful without them and represents a threat to them. There are definitely a lot of neo-Nazi's out there, but Pewdiepie isn't one of them, and when media outlets lash out at him like this they just end up looking more and more desperate each time. He's made some mistakes, and this was one of them, but it shows that he's sloppy, not racist.
I am disappointed that he didn't vet these people better though. I mean come on, you're promoting them on your channel, at least make sure you REALLY like them. When he denounced the channel, it did make you wonder why he promoted it in the first place, like is he just willy nilly picking channels he saw one good video on? Make sure you like the whole channel before you promote it, otherwise just promote the video you thought was good instead of the whole channel. He says he'll be more careful from now on, and I believe him. He's never been a thorough, professional sort of guy, so he keeps making these sloppy mistakes that he learns really slowly from.
Personally I don't watch his stuff, but he's a big enough presence that it's hard not to know about him if you frequent Youtube. I originally hated him for being so overrated, but I don't anymore. If people like someone or something, leave them alone about it. I used to be on so many hate bandwagons before I finally got sick of it. Now if I hate a person or thing, it's my own opinion on their merits. Justin Beiber? His music is pretty trash, but he's an okay guy, don't throw water bottles at him, that just makes you a jerk. Nickelback? Eh, some of their songs are okay. Not really my cup of tea, but if you like them, you do you. Pewdiepie is mostly pretty boring to me, but more power to him that he's found the success he has. He's increased gaming's footprint on the cultural landscape in a mostly non-toxic way. He seems like a nice guy, just kind of dense at times. He gets himself into so much trouble with his carelessness, so I can understand why some people grow tired of him and why advertisers find him toxic. It's not fair to call him a racist or a nazi though.