I've tried adding the Revit 2017.1 updates .exe in under "install additional software" and it worked, but came up with a dialog at the end of the install, so it wasn't silent. You can still add it in if you want using that method, use the /qn switch, as long as you don't mind clicking on a dialog box or two.
However, what if you want it all silently?
I had to extract the .msp file from the .exe, then include it in the .ini file. The PATCHES= line was missing so I had to add it.