Jurgen Klopps side produced a spirited performance in the first leg of the semi-final but spurned several golden chances at the Nou Camp as Lionel Messi went on to inspire Barca to a 3-0 victory.
Ex-Liverpool striker Luis Suarez broke the deadlock midway through the first half and Messi stunned the Reds with a mesmeric double in the final 15 minutes of the clash.
Though Roberto Firmino and Mohamed Salah have been ruled out of Tuesday nights second leg, Gundogan believes the tie is far from over.
The City midfielder told DAZN: Ive already thought about it and somehow I have the feeling that its not over yet.
I can even imagine Liverpool winning the game 4-0 at home.
I dont know why, but I think that at Anfield, and Klopp as a motivational machine and with the types of players that are very unpleasant to play against, even a team like Barca can be completely shut down in one game.
Klopp insists that Liverpool have not given up in their quest to lift the Champions League trophy after falling at the final hurdle last season.
We are far away from giving up. There is hope, he said.
If there is an opportunity to go to the next round, we have to try.