Roy Hodgson's men are given little chance of progressing deep in Brazil, having drawn Uruguay, Italy and Costa Rica in Group D.
Cahill, 28, said it was an open tournament with several teams capable of going deep at the showpiece event.
"It’s so open, with so many good teams there. In that respect it's like the latter stages of the Champions League, with so many good teams out there," the Chelsea defender said.
"If we went forward, would it surprise you? No. If Brazil did, would that surprise you? No.
"A lot of teams could go a long way and it wouldn't surprise you – and we're certainly in that category."
Cahill said his move to Chelsea from Bolton in January 2012 was the opportunity he needed on the big stage.
"That experience and maturity comes as you play more. I'm 28 now, I've played quite a few big games in the Premier League and Europe," he said.
"Obviously as a player you're self-confident in the ways you train with people and play with them, telling yourself, 'I can reach their levels, I can get there', without being arrogant about it.
"But you need an opportunity and Chelsea gave me the opportunity to play on this stage.
"It might seem a bit weird but I feel I was doing similar things at Bolton without people noticing. At Chelsea nearly every game is televised live, you're in big games, and people see a lot more of me."
Cahill praised his central defensive partner at Chelsea, John Terry, for the influence he has had on his career.
"Playing alongside John rubs off on you, it's bound to," he said.
"Secondly, it’s about adding the hunger.
"It’s easy when you’re playing well and winning games. Then nobody needs to be shouting and bawling.
"You do it without thinking sometimes because that hunger, that wanting to win and do well, overrides the other feelings."
