Credit has to go to all involved. Vince McMahon gave Hogan, Austin, Rock, Cena the platforms and means to be successful, but it was their skills and intangibles that really made them superstars.
You could name an endless parade of names Vince McMahon wanted to see become mega stars that never made it, simply because they lacked the perfect combination of look, ring and mic skills, and charisma to get to that next level.
I think of those you named, Vince really owes the most to Hogan. For as much as the IWC, myself included rag on Hogan these days, his contribution to the WWE and to professional wrestling are unquestioned. He put the WWE on the map, and really made pro wrestling an acceptable medium on a national level. He was the first wrestler to really break down the stigma and barrier of what a pro wrestler was, and he was really the first to transcend the business and become a true household name. He was the perfect person for McMahon to build the WWE around at the time, and it was his drawing power that created the interest and revenue that helped the WWE become what it is today. So no matter what Hogan is as a person, or is to the business in 2012, both he and McMahon owe each other more than either will probably ever admit.
With Austin, I think Vince really did help make him. Austin bounced around from WCW to ECW, with marginal success, but never had the full trust and enthusiasm of a promoter to be allowed to become anything more than a midcarder. Vince definitely knew what he had in Austin, and he used Austin's natural strengths as a performer, as well as a character that was just an extention of Austin himself, to really tap into a good counter balance against WCW. Austin, without a doubt in my mind made the Mr. McMahon character. I'm not sure anyone else in WWE could have been the foil that McMahon needed to get his own character across, and the way they gelled throughout their feud was a testament to how much each believed in the other. Austin helped save the WWE in an era where it was languishing, and Austin made it possible for Vince to live out his on air dreams, so again I guess both truly owe each other.
With Cena, I think he owes Vince everything. As time has gone on, we've seen that a lot of the fan base has turned away from him, and in many cases, that would be enough for Vince to pull the plug. But he knows that with Cena, that polarizing appeal he has brings something to the table. It makes for those iconic moments like Cena at One Night Stand, or Cena/Punk at MITB. Plus, as much as Cena does do for WWE, Vince has chosen to continue to build the company off of Cena's back, when there is talent like Punk, Orton and others still rising to the next level with which he could use as the foundation.