Giggs, named as captain for the evening, delivered a virtuoso display in the contest at Old Trafford as United set up a fourth-round home clash with Fulham.
And referring to the 39-year-old after the game, Ferguson told MUTV: "He will play for another year.
"There are no signs of tiredness or weakness in his game, his quality is still there, he has fantastic balance and he has appetite for it.
"He is just an incredible human being."
United's goal came in the ninth minute from Wayne Rooney, who was back in action after sitting out their last five matches due to a knee injury.
The England striker turned in Javier Hernandez's square ball from close range, and after taking the congratulations of his team-mates, then paid his respects to his late sister-in-law, kissing his hands, looking to the skies and raising his arms as he walked back towards the halfway line.