Gates came second in Pop Idol in 2002 at the age of 17. Speaking to OK about the latest talent show winner, he said that Cardle should "enjoy" the experience.
"I think Matt will do well as he's a little older," he said. He'll have more of an idea what he wants to do. [I would tell him to] listen to advice from other people, but it's important to know your own mind as well - and enjoy it!
"I was lucky enough to travel the world after Pop Idol. It was an incredible experience."
Speaking about his post-Pop Idol career, he added: "I think people forget I was 17 during Pop Idol - I'm 26 now so of course I'm not the same shy teenager that the world saw then! I don't feel pressure to be honest.
"I'm a lot more confident. Each time I tick something off it's something I have achieved. I'm only 26, I've got lots of more things I want to do and lots of time to do them."