"I think the England goalkeepers who have come in for criticism recently are bloody good goalkeepers," said Keane.
"He has all the attributes he needs to get to the top and he has got the right mentality too.
"I don't think it's right for me to say that he is the best goalkeeper, but we know that he has massive potential and he could go on to become the best.
"He has an inner confidence that says 'I know I'm good, but I'm not bragging about it' and that's something that all the top players have."
Keane says Gordon's temperament has helped endear him to the fans.
He told the Sunday Sun: "We are hoping that our goalkeeper will prove to be a top goalkeeper for Sunderland.
"Over the years, Sunderland fans have always loved a striker, a goalscorer, and hopefully that will never change but you can love goalkeepers as well, and I think they have taken to Craig.
"In training, he is very unassuming and he just quietly gets on with being a player and a top goalkeeper.
"The fans like that, it shows you don't need to be flamboyant or have a different haircut every week.
"Craig is quite different to a lot of the goalkeepers that I have been involved with in that he doesn't seem to get too high or too low.
"He's got the balance right, and that's something we are all striving for.
"He's at a good age, he has got a lot of games behind him up in Scotland and he has played in some very big games for his national side and come through them with flying colours."