Nothing in the slightest bit unusual about this. He's growing exponentially because he's the number 1 in his niche, i.e. Spanish LPers. Some people can't even watch English LPs because they don't understand the language, so the Spanish LP market isn't quite as saturated as the LP market as a whole is.
Also, just because a market is saturated doesn't mean someone can't blow up and get millions of subscribers and such. Gaming channels are part of the entertainment genre, and like most any entertainment, people like to watch lots of different shows, with lots of different people. I'm probably subscribed to a couple hundred or more gaming channels just myself, which is a sizeable chunk of the total channels I'm subscribed to.
Channels are driven by the quality of their content not language.
Language is part of that. If you only speak Spanish, then I don't care how great some English/American LPers videos are - they're unwatchable because you can't understand.
If he's getting that many views and subscribers, then he
does make quality content. It's like someone like PewDiePie, a lot of people would argue that his content is no longer quality compared to his older stuff. I personally prefer his older videos - but does that mean his content is suddenly bad? No it just means the niche he is targeting has changed since he initially started. Just because someone's channel doesn't fall into the particular niche you like best, doesn't mean their content is bad. People are there to be entertained, sometimes they like over the top silliness.
Also, by your posts I'd guess English is your first language. So that means Spanish isn't your first language and so you're judging his videos off a language you that isn't your primary one, or perhaps isn't even one you can understand at all. So how are you able to judge if it's quality content from that exactly? That's another thing too - humour differs in different countries, what might seem like a terrible joke and not entertaining to me as a Brit, might go down hilarious with someone in another country, etc.
No he's not botting. If you aren't convinced, go to any one of those videos and check out the comments. There's a new comment roughly every 30 seconds. These aren't bots, these are real people who enjoy his videos.
The numbers aren't that surprising anyway, PewDiePie saw larger and quicker growth than this guy, and you agreed that was possible because of the market not being saturated, but the market for Spanish LPers was clearly not saturated because he's the number one Spanish LPer and only has 9M subs (compare that to the number 1 US LPer, etc).
tl;dr: Nothing unusual here.
Also, just since you asked nicely..
Please point me to a similar channel that garners the same amount of views and subscribers, excluding Vanoss because that channel is mainly collaborative.
elrubiusomg
canalcanalha
whinderssonnunes
slivkichanel
eeoneguy
authenticgames
leafyishere
...I could keep going.
People make the mistake of assuming that growth is dependent on your total subscribers or views, but growth depends on a lot of factors. There were times for example when PewDiePie was getting 80k+ subs a day, but now he's getting less than the people I listed above, despite still being a bigger channel than them.
If growth purely depended on size then the list of top YouTubers would be the same 10 years from now and there'd be no hope for new YouTubers to climb up those ranks. The truth is that's not how it works, and when someone snowballs during their new growth at a time of peak discovery they can easily start to climb those top 100 ranks and push to be up there with the other big players.