Currently situated one point behind the Shaymen in their final Group D encounter, who also boast a stronger goal difference, Newcastle's second-string are required to win after 90 minutes to reach the last-eight for a second consecutive campaign.
The young Magpies faced Halifax Town in last season's competition, coming from behind to record a 2-1 victory at The Shay and Heffernan, who captained the visitors that evening, is hoping to take inspiration from their previous encounter and become one of two under-21s sides, including West Ham United, to reach the knockout stages.
The Cork-born defender, who joined United in the summer of 2023 following his departure from AC Milan, told newcastleunited.com: "We know it will be a difficult game but knowing what we got from them last year, we know we have the quality to beat them which is good for our confidence heading into the game. We're looking forward to it and there is no reason why we can't win.
"We know it's a big game because we want to progress. We won our first two games (against Gateshead and Boston United) but lost against Scunthorpe so we know we need to win this to go through. Everyone wants to progress and understand what is on the line.
"We were disappointed with the result at Scunthorpe (a 2-0 defeat) because we felt, after the way we played in the first half, we should have been leading at half-time. It's now all focus on Halifax and we have to redeem ourselves."
Heffernan, a representative of Republic of Ireland from under-15 to under-19 level, has relished his involvement in the National League Cup so far this term, starting all three of the young Magpies' group fixtures whilst wearing the captain's armband.
The 20-year-old centre-back, who netted the winning goal in Newcastle's 4-3 comeback victory against Gateshead in August, believes the squad are more than capable of completing a positive run in the competition should they overcome Halifax Town on Tuesday evening.
"There's been a lot of learning from these games," he added. "It's tough opposition with a different type of football compared to a Premier League 2 game. You learn a lot and the likes of Halifax and Scunthorpe are strong sides so it's good games to play in.
"Everyone has ambitions and, with the squad we have, I don't see why we can't win it with the players and quality we have. That should be an aim if we can get through the game at Halifax and progress. I don't see why we couldn't go further in the competition."
