There is no more evidence for Gillian dating PM, but most of all, there is nothing encouraging such a ship from Gillian or PM.
At least, with Gillovny, we can all agree that Gillian has publicly expressed she is okay with the idea, either you believe it’s a game or not, she does have fun with it, tease the fandom with Gillovny and somehow, encourage the ship. That’s why we all feel comfortable believing what we do, and shipping them with no shame. But Gillian never said anything about Peter Morgan at all, personally wise or professionally wise. So I find it extremely borderline to say she is in love when she might not be, that she has heart eyes when she clearly does not, that he’s the One and she’s going to raise his kids, when she actually could as well be in a relationship with someone else, or be single if that’s what you believe, or whatever. All this ship is quite disturbing and slightly disrespectful considering the absence of communication from Gillian.