He denies being a member, of course. Nazis, upon extradition to The Hague to stand trial for war crimes, denied being Nazis too.
In Gorka's case, the Hungarian Nazi organization has affirmed his membership. Not only that, but Gorka actually signed his PhD dissertation "Sebestyén L. v. Gorka”, where L. v. stands for that Nazi organization.
That Breitbart, where Gorka worked before being brought to Washington by Steve Bannon, is an extremist White Nationalist site, is beyond dispute. So is the fact that Gorka is a Nazi. I don't judge him by what he is saying. I judge him by what he has actually done, and the evidence against him is overwhelming.
Queue Trump supporters claiming that this is a plot by the Jews to destroy the Trump Presidency in 3, 2, 1........
Top Trump aide wears medal of Hungarian Nazi collaborators | The Times of Israel