The pin is small but is driven out easily enough. If it is a roll pin a roll pin driver might be better but a normal drift punch should work. Now the broken front "leg" is a different story, because they fit into a blind hole. Sometimes they can be removed by just a sharp rap on the top of the frame with a plastic hammer. But I have seen them stuck so tightly that the only recourse was to drill a small hole in the frame up from inside the magazine well and drive the broken part out. You have to start the hole with a Dremel tool and then use a long drill bit. Once the broken stud is out, drill the hole from the top full size until it breaks through the frame. That way, if you ever have the problem again it is easily fixed.
Broken ejectors were a real rarity when they were milled from steel stock, but when some makers started to cast them, trouble started. Good luck!
P.S. I don't recommend trying to drill out the broken stud from the top. The ejector stud is harder than the frame and it is too easy to have the drill wander and come out the side of the frame.
P.P.S. I don't know why they didn't just drill that hole through to begin with; apparently no one considered a broken ejector to be possible. Oh, and Kuhnhausen, guru of all gunsmithing on the 1911, warns to use caution in removing an ejector as the stud can break off inside the frame. But he doesn't say what to do if that happens!!
Edited to add: "use a bit of Loctite..." That will make an ejector, even an unbroken one, almost impossible to remove and there is no need for it.
Jim