Does the employee HAVE to be based in the US? I ask because Brazil is a big country with relatively few direct international connections to US cities, aside from the hubs of GRU and GIG. A possible alternative would be Panama City. Copa Air flies out of PTY and serves a large and growing number of Latin American and US cities. Their airfares are generally reasonable and Panama City would be a great place to live IMO, certainly preferable to Miami or Houston.
If the employee has to be based in the US then I agree with guv1976 that MIA likely has the most direct connections to Brazilian airports other than GRU & GIG. MIA also has a lot of direct flights to Central America and, I presume, to Mexican destinations other than MEX.