What do supervisors have to gain from a success or failure of a PhD student?
First, to answer the question directly, supervisors have much more to gain from successful students than unsuccessful ones. Among other things, success brings them new students and future collaborators. Most of us are very proud of our successful students and, we hope, they have good feelings toward us, as well. The failures just disappear. 

Moreover, I doubt that he would want to keep you "under his thumb" rather than letting you go, whether from passing or failing. I think that it is very unlikely that any student, no matter how badly treated, can "ruin the reputation" of their advisor unless there is a pattern of abuse over many years and many students. I'm sure it happens, but is so unlikely that it would be an extreme event if he considered it to be a possibility. 

But, it is also possible that he just wants you gone, however it happens, because he sees you as a thorn in his side and he is tired of dealing with it. It is possible that, while failing you is a poor alternative, he sees it as the only way. That doesn't imply that he is correct, though he may be, and that you are wrong. But it might just be more peaceful without you. Your statement "all the PhD has been done without following any of the supposed methodology and criteria" is a bit of a red flag. 

I worry, however, that you may be fighting him just for the sake of fighting. He seems to have "expected" some changes. It seems you have resisted. I can't judge the case, of course, but it is a poor strategy to fight with your supervisor rather than seeking some accommodation. 

I don't know what options are open to you, but most seem dire unless you find a way to make peace. Abandoning years of work is difficult, but may be necessary if it hasn't been productive. Even established researchers have to do that on occasion.