Bologna struggled in their Champions League campaign, crashing out from the league phase with only one win in eight matches.
But Tuesday's victory over a top-three Serie A side would boost the team's confidence, the coach said.
"We played for history and we succeeded," Italiano told reporters.
"This is a beautiful moment, it always pushes you to give your best."
Italiano said winning at Atalanta made the result more special.
"I think it gives you self-esteem and awareness, you can see that there is growth. The Champions League gave us a big hand, this is a group that is constantly growing... it's not easy to play in Bergamo," he added.
Bologna will face the winner of the February 26 quarter-final between Juventus and Empoli in the semis.
"The club had this dream of getting as far as possible in Coppa Italia. Right now we have achieved the first goal, now we are waiting for the next opponent," Italiano said.