"We have taken an awful lot of positives out of Saturday. Other people may not have, but we think we can go there and do it," said Duff.
"We just have to go there and enjoy it - we still think we can do it, so bring it on."
Asked if it would be the nation's greatest result on the back of the 1-0 first-leg defeat at Croke Park, Duff replied: "Ever, without doubt.
The Fulham player, who is in line to win his 80th senior international cap in Paris, is one of the men in the current squad who played at the 2002 finals in the Far East.
However, despite his lengthy career, which has taken him from Blackburn to Chelsea and then Newcastle before his move to Craven Cottage, he cannot remember being involved in a situation similar to the one Giovanni Trapattoni's men face on Wednesday night.
Duff said: "I was actually thinking about that this morning when I woke up.
Ireland have a chance only if they score the first goal and that might make the French and the crowd nervy. Freaky_Joe "I don't think I have gone away behind looking to resurrect a tie so to speak, so it's new to me and I am sure it's new to an awful lot of the lads.
"We have obviously given ourselves an uphill task. Away goals are a massive thing in football but, if we go over there and nick one, it is game on again.
"We are all confident we can go and do it. You have to be."
Nicolas Anelka's goal in Dublin handed the French a first-leg lead and the Republic know they will either have to win by the same scoreline to force extra-time and penalties, or score at least twice to go through.
That may be a big ask but they found the back of the net in four of their five Group 8 qualifiers away from home, including their trip to world champions Italy, and created several opportunities on Saturday.
Duff added: "They did have an awful lot of possession but, when we did get in about them, we did create things and I think we can do it again.
"One goal and it's a draw, so we are looking for two or even three, so even if they score another one and we win 2-1, we are through."