Darwin looked at the structure of change in populations (which is what the Scientific Theory of Evolution is all about). He didn't know about genes, as the DNA and genes weren't discovered until a long time after his death. Darwin's theory stands on the observations of his day. If he knew more of the research that has been done since, he would have been able to expand on his model, but it wouldn't have changed much.
This is like asking if the Wright Brothers would have changed their idea about flight if they had known about the jet engine. They would have been able to build a bigger, stronger plane, that's all; they would not have changed the idea of flight of the basic processes of flight. On the other hand, the Wright brothers writings are not closely consulted when designing space shuttles; we don't have to worry about whether flight is possible. It is kind of the same with Evolution. Science looks at the new information, not the stuff that has long ago been established because it already have been proven many times.