Can an illegal with no visa marry and get citizenship?

Obviously this is totally illegal. Here's the thing, the only way for you to stop the situation is to a) reason with your friend (which seems to not be working) or b) turn him and the girlfriend in for fraud. I doubt that this will get a result that you want as your friend will be deported and could face 2 years in prison and so could is girlfriend. The brazilian attorney faces no legal recourse here in the US for his actions so he clearly doesn't have your friend's best interests at heart. Maybe you should suggest that he consult with a US attorney to get the opinion of an attorney wo is actually licensed to practice in the US. If this Brazilian attorney is also licensed in the US, I would turn him in to the bar association of his state.