The North-West outfit had been enduring a tough time of it in the Championship after going nine games with success, but their 3-0 triumph over Fulham on Tuesday has lifted spirits at Ewood Park ahead of their meeting with the Premier League side.
Last season, Rovers enjoyed victories against both Swansea City and Stoke City in the FA Cup before losing to Liverpool, and Duffy believes that they can replicate their results from 12 months ago providing that they approach the fixture in a positive manner.
The 24-year-old said: "We can go and enjoy it, we did it last year here," he added. "Hopefully we'll get a good crowd and they back us.
"They are a good team but this is the FA Cup, we've got a bit of confidence after the win over Fulham and we can go and take it out there to show West Ham how good we are."
Duffy missed the end of last season, but he has re-established himself in the Rovers starting lineup during the current campaign.
The former Everton trainee has scored two goals in 28 appearances in all competitions, including his side's second in the win over the Cottagers.