Kjellberg is clearly straight-up wrong when he says this is "an attack by the media to try and discredit me, to try and decrease my influence and my economic worth". However, I think the media coverage of him has been far from irreproachable, in a way that could have serious consequences.
I'm inclined to take the guy at his word when he says that
You might make an argument that Kjellberg is a "straight-up racist", and I think that argument is not entirely without support, but none of the articles I've seen have really made a solid case for it.
On the other hand, there most definitely is a case to be made in that these kinds of "jokes" act to normalize hate speech, and that this kind of thing can lead to serious social malaise; I think the Buzzfeed piece that jabrams007 just linked makes this case pretty well. In particular, I think this point is important:
In addition to failing to get to the crux of the issue, some of the coverage is unfair or misguided in a way that could be seriously counterproductive. You can kind of understand where Kjellberg is coming from in being upset by the media; see, for example, the previous headline of the Wired article Ikatono linked earlier; the title being
"PewDiePie Was Always Kinda Racist—But Now He’s a Hero to Nazis"
Also, look at this quote from the article:
Clearly if Kjellberg had, entirely by his own initiative, decided to use an image of Leslie Jones in place of Harambe, that would indeed be pretty terrible and a strong sign of racism. However, from the video, that's quite a misleading description of what happened. Apparently the image of Leslie Jones came up as a result of his typing "what if Harambe was alive" into Microsoft's Project Murphy; presumably Project Murphy's association between the two was the result of last year's harassment campaign against Leslie. Sure, you can argue that the description is still factually correct, since he did indeed "repeatedly use an image of actress Leslie Jones to depict Harambe", as he chose to include those images in the video. But there is also a big difference between the natural reading of the text and what it purports to describe, so the description is unequivocally and seriously misleading.
Apart from the obvious harms that can come from media bias as a general phenomenon, in this case it also lends credence to the alt-right narrative that the mainstream media is simply "fake news". Clearly this doesn't matter for someone who has already fully bought into this narrative, but as the Buzzfeed article highlights there are plenty who haven't but could easily be susceptible to it.
When you vilify someone like PewDiePie you are essentially drawing a boundary and attempting to force some of these people to take sides in a battle for hearts and minds, and when some of that coverage is unfair or biased you're also giving the other side serious ammunition in that battle. When you consider the fact that PewDiePie has upwards of 53 million subscribers, it's also clear that the stakes in this battle are quite high.
So yeah, I'm all for a discussion on the potential harms that can result from normalizing hate speech, but it's also a discussion where nuance and careful deliberation is of the utmost importance. This is the kind of shit that can backfire hard, and has already done so in the past.