No. First, as said that’s not what Social Darwinism is; Social Darwinism is a political attempt to cash in on the prestige of Darwinism, and to distort them for profit. And second evolution is a description of how things work, not how they should work; you don’t have to deny how things are to want them to be better.
It’s not very accurate, because corporations are controlled by humans, who are self-interested intelligent creatures capable of foresight, planning and cooperation. They can and will game the system to make a profit, or simply to preserve their jobs; they aren’t going to just let some “unfit” corporation they are working for collapse out of some abstract dedication to Darwinian fitness.
It depends on what you apply it to. Treating ideas or organizations as expendable things to be judged and kept or discarded on how well they do is ones thing; treating human beings that way is another. Consider a subset of society, science; scientists put theories through a selection process to determine their “fitness” (aka test them to see if they fit the facts) and discard the ones that fail, something roughly analogous to natural selection; they don’t shoot scientists whose theories fail the tests, however.