I really hate to splash you with cold water, but this quote doesn't mean what you think it means. Mussolini and Gentile used the term "corporate" (as translated from Italian with meaning lost in the translation) as the "body" of the state which "incorporates" all of the classes. Thus, fascism created a "corporate" state.
You are trying to take translated Italian rhetoric of the 1930s and force fit that round peg into the square hole of today's politically-mangled usage of those terms. That can never end well.
Mussolini and Gentile (and Hitler) presumed that all businesses and corporations would be subservient tools of the government. Mussolini had his "Ministry of Corporations" to keep all commerce under a tight rein. Hitler, of course, put all business under the direct control of Herman Goering.
There was no sharing of power with corporations. There was never any intention of allowing business leaders to have any say in the government. You misunderstood the use of the word "corporate."