i'll take 5 sources as fact, you can question it if you like.
also, Trump's lawyer's representative didn't deny it, just attacked "FBI leaks"
I suspect it's probably true but that doesn't make it fact. If true, it indicates that Trump's handling of the Flynn affair was a gross & possibly fatal error even if charges of personal collusion are found to be groundless.
He can't throw Flynn under the bus & try to stop the bus from having its way with him. His only legitimate course was to look Flynn in the eye & tell him he'd never do a day in jail. His powers of pardon are absolute.