I don't have numbers, but in my experience I'd say "a lot." The freelancers I know try to get US customers because they get paid more.
Companies may hire remote non-citizens as contractors because that avoids any real or perceived labor law, visa, and tax issues. If they have actual employees in other countries most likely that's through a branch office.
I think most of the remote non-citizen employment happens through what we call offshoring. US companies contract with software shops and agencies in low cost of labor countries with no huge language barrier -- India comes to mind. The people doing the work aren't employees or freelancers, they are like factory workers making shoes for Nike in Vietnam, employed by a local company that contracts out for work. With that setup only the managers need to speak English.
Companies may hire remote non-citizens as contractors because that avoids any real or perceived labor law, visa, and tax issues. If they have actual employees in other countries most likely that's through a branch office.
I think most of the remote non-citizen employment happens through what we call offshoring. US companies contract with software shops and agencies in low cost of labor countries with no huge language barrier -- India comes to mind. The people doing the work aren't employees or freelancers, they are like factory workers making shoes for Nike in Vietnam, employed by a local company that contracts out for work. With that setup only the managers need to speak English.