I think that in the US there are about three million programmers, of whom maybe 10% use Emacs, or about 300,000. There are about 110,000 NCARB-registered architects in the US, and presumably the number of architects is similar to the number of current AutoCAD users (of whom most of each group belong to the other.) But wait! The US Census Bureau estimates the number of US architects at 141,000.
So I thought at first that the answer was obvious but now I don't anymore.