Claims that "Antifa" was responsible for the Capitol Riot

Here's an actual antifa-type person who was on the front lines at some points.

John Sullivan is the founder of the civil rights group Insurgence USA and does not align politically with President Donald Trump, but has been in D.C. this week for several planned protests including Wednesday’s rally at the Capitol.
“Protesters weren’t really, like, trying to burn anything down, they weren’t really trying to break anything, their main motive was to make it into the chambers,” Sullivan said.

And in that process, one woman was shot and killed, and Sullivan was standing right next to her when it happened.

“I remember looking into her eyes and seeing the lifelessness and understanding that she was dead,” he said.

He does not seem to have been pretending to be anyone, or encouraging anything. His presence doesn't demonstrate he was some kind of driving force, but it's certainly being presented as such.
John Sullivan and his methods are almost universally rejected by the antifascist activists who most people would consider to be "antifa".
He was certainly not a driving force.
I know activists who have had various interactions with him, and to be frank, he is generally considered to be an idiot who means well.
Trying to convert working class fascists to anti-fascism (and anti-capitalism) is a tactic used by anti-fascists since Musolinni's earlier days. But Sullivan convinces nobody. He hangs out with fascists and the fact that they don't hospitalize or kill him shows that they in no way consider him to be genuine antifa.
Word is that Epps is an Oathkeeper. Fascist rather than antifascist. In fact Oathkeepers sometimes head to Portland to literally hunt antifascists.
I think the simplest explanation for him appearing to be protected by the FBI is that he's fully cooperating with their investigation.