I guess it depends on who you talk to, but plenty of Americans and Westerners are aware of this shit. As for a “firewall”, there is nothing blocking us from crap like Voice of America. So there really is no buffer, unlike other countries such as China or Russia, attempting to keep us unaware. The government just doesn’t mention it.
If you’re getting your news from social media, you’re an idiot, regardless of who’s propaganda you choose to consume. Just look at Trump supporters.