Bruce's side put three goals past Sunderland at the KC Stadium on Sunday to move into the final four of the cup for the first time since 1930.
Even though Hull sit 13th in the Premier League in their first season back in the top flight, Bruce believes there is work to do to avoid an immediate return to the Championship.
They return to league matters on Saturday with the visit of title contenders Manchester City, and Bruce has targeted at least two more wins to secure their Premier League status for next term.
"I still think we've got to win a couple more games," he said.
"We're a newly promoted club and we've made huge strides very quickly but there is still work to do and it carries on.
"We have to get ready to play Manchester City at home. But that's the Premier League - we have to address that and make sure we stay here and get better and better."
Hull have shown inconsistent form in the top flight of late - winning twice, losing twice and drawing once in their last five outings.
