The screen legend - who has been openly gay since 1988 - has offered his words of wisdom to his "X-Men" co-star and promised "everything gets better" from now.
Speaking to "Bridgerton" star Jonathan Bailey for the February (21) issue of Attitude magazine, he said, "Everything gets better (when you come out because you get self-confidence). You get better in terms of relationships, friends of all sorts, family, if you're lucky. And in my case, I think in every case, your acting is bound to change and improve."
The "Lord of the Rings" star did, however, admit he was "disappointed" in himself for not recognising that Elliot - who was formerly known as Ellen - may have been struggling with his identity on the set of 2006's "X-Men: The Last Stand".
"I remember Elliot Page, in one of the X-Men, sat as close as we are now. And I had to speak when they'd finished, and I couldn't hear what they were saying. Nobody could hear what they were saying," he recalled.
"So, I said, 'Look, if you can't speak up, would you mind when you're finished speaking, just dropping your hand so I know when you've finished speaking?' And then they came out (as gay) years later and suddenly you couldn't stop them talking. You heard everything."
"And now … they're Elliot. And I'm so happy for Elliot. And so disappointed in myself that I didn't detect what their difficulty was with communicating."
Elliot - who is married to dancer Emma Portner - announced in December (20) that he had changed his name and that his pronouns are he/they.