The market for Portuguese language teachers in the US would depend heavily on where OP lives, and they might have better prospects moving to a different city. I would think a large city like Chicago would have some demand, but perhaps not as high as Miami given the population of Brazilian expats and tourists in Miami. And either of those would probably be higher than, say, Crosby, North Dakota unless Crosby quietly has a large immigrant community. Still, moving within the US for work is probably much easier than moving from the US to Brazil.