Smith was one of the better players on display at the Den on Sunday when Millwall were held to a 0-0 draw by a battling Rovers display that now means the two clubs will do battle once more at Ewood Park on Wednesday evening.
Wigan await the victors in the semi-finals, with either Manchester City, Chelsea or Manchester United the big-name finalists in waiting.
The visitors did not manage a shot on goal on Sunday whereas Millwall should have secured the win, only for on-loan striker Rob Hulse to balloon a close-range effort over the crossbar.
A 2-0 league victory at Ewood Park earlier in the season is the basis of Smith's confidence and he knows all the Lions have to do differently from the original tie is convert their best chances.
"When we played them away we were the better team and we won 2-0 so we go in to the replay with confidence," he said.
"They haven't scored against us yet in the two games and we know we can create chances. We just hope we can put a couple away this time."
Kenny Jackett's side have struggled for results in front of their own fans recently, with the notable exception of the 2-1 victory over Aston Villa in round four, and Smith admits it can be harder to perform with an expectant crowd.
"There is a bit more pressure at home perhaps," he said.
"Last year it was the same. We lost four at home previous to this one so we needed to get the fans back on our side and we put it all in to our performance.
"We were unlucky not to win. In the two games I thought we edged them both so we go in to the replay with confidence. They haven't beaten us yet and hopefully that will continue."
Blackburn boss Michael Appleton accused Millwall of deploying 'cheap shots' against his players to get the upper hand.
Rovers are still yet to concede in this year's competition and, although a replay was not his first priority, Appleton is pleased to still be in contention at this stage of the season.
"Obviously before the game I wouldn't have wanted a replay but we still have a chance to go and play at Wembley," he said.
"I'm sure both football clubs are delighted that they've got a second bite of the cherry and they'll be doing everything they can to get through the tie.
"The thought of playing a semi-final against Premier League opposition is a huge incentive for us."
With both sides struggling for league form a replay would have been the last outcome some would have liked.
But the pain of fixture congestion will be eased by the knowledge both clubs will receive £116,600 for the live broadcasting rights, with the replay being shown on ESPN.