It's from a 19th century novel by Dinah Maria Craik, sort of, who apparently has a few other quotes running around that get attributed to Eliot.

"You mean, Mr. Halifax, what I might have been. Now it is too late."

"There is no such word as 'too late,' in the wide world -- nay, not in the universe. What! shall we, whose atom of time is but a fragment out of an ever-present eternity -- shall we, so long as we live, or even at our life's ending, dare to cry out to the Eternal One, 'It is too late!'"

This is not to say that Eliot definitively didn't; nobody seems to have been able to find a source for sure, but that one seems likely.