Hardly. Based on past performance my money would be on Trump making an innocent mistake before I'd bet against Assange.
“Except Assange clearly lied as Donald is saying indeed the source was Russia”
Actually Assange said HIS source was not Russia or a state actor but an individual. He DID say he didn’t know how his source came about the leaks.
Maybe Assange doesn't know who the hackers are.
He may only know know who passed them along to Wikileaks.
His credibility is now destroyed.
No more than anybody else in the media who doesn't reveal his sources (and that's assuming he knows who they are).
If he had to say exactly where every document came from (assuming he knows), nobody would bother leaking documents and his site would be out of business.