Ben Domenech said Sunday on CBS' "Face the Nation" that McCain is "very grateful for the chances and fortune that he's experienced in life. He's reflecting at the end on a lot of different things."
Domenech publishes the online political and cultural magazine The Federalist. He's married to McCain's daughter Meghan.
The 81-year-old senator was diagnosed in July with glioblastoma, an aggressive brain cancer.
Domenech says, "We appreciate all of the support that we've been given by a lot of different folks who have come out and met with him over the past couple of weeks."
McCain left Washington in December and hasn't yet been able to return.