The only people in America who have heard about the Orthodox Church, by and large, are people who have attended a Greek festival, or know a Greek person who is a believer well enough to have had at least a brief discussion about it. So I would estimate that maybe about 1% of the American people who are not Orthodox have some idea that there is a Christian body called Greek Orthodox. As for Orthodoxy per se, I would say .5%.
This has been my experience.
'Orthodoxy in America' is a non-issue for 99%-99.5% of Americans.