Obviously not everyone who watches him will do shit like this but PDP is a person with a LOT of influence, which he has used to signal boost some really disgusting views to lots of impressionable fans including kids and people who are mentally unstable or are already massive bigots.I see pewdiepie and I have no urge to be killing people, I'm not anti-semitic and not racist.
Now, I will not say he haven't done some disgusted shit, he did. But the people that does things like this are already mentally sick, they would probably do it with pewdiepie videos or not.
At best he could use his influence to instruct young generations that this type of behavior is... inhuman... disgusting... i don't know...
He gets called out for this crap, he makes a shitty non-apology and then gets more alt-right bigots and shitheels on his side. His fanbase grows increasingly toxic and more emboldened because he is getting away with promoting hate speech under the guise of "It's just a joke guys!"
His complete lack of remorse or willingness to be a good role model does make him culpable for shit like this. And it's just going to get worse when people who agree with the shooter are going to think that they can rally under PDP's banner and influence even more vulnerable or disgusting people