The Hibees striker scored a penalty when the Championship side romped to 3-0 win over the Taysiders in the League Cup quarter-final tie at Easter Road in November.
United’s season has deteriorated further since and they travel to Glasgow bottom of the Premiership, eight points behind Kilmarnock with five league games remaining.
However, Cummings, who has notched 23 times this season, believes it will be their drubbing by Hibs which will preoccupy their minds at the national stadium.
The 20-year-old told Press Association Sport: “They have been struggling a bit this season and they have lost the majority of games they have played and we have won the majority of games we have played so I think that will come into play a wee bit.
“And I think it will be in the back of their minds, the fact that we have already beaten them 3-0.
“That night we were different class and we battered them off the pitch. It was a comfortable 3-0 and it could have been more.
“I think that is massive for us, the fact that we have already beaten them and beaten them comfortably.
“The boys will go into Saturday knowing we can do it again and I am buzzing for it.”
Hibs’ form, however, is as as poor as the Tannadice men as they sit third in the Championship which has already been secured by Rangers, who play Celtic in the other semi-final on Sunday.
Alan Stubbs’ men have won only two of their last 11 games in all competitions.
Cummings grabbed a double against Falkirk at Easter Road on Tuesday night but the 10-man Bairns fought back to draw 2-2 and stay six points clear in second place, albeit having played two games more.
He said: “I am quite a big critic of myself and I am not really happy with the amount of goals I have scored in the last couple of months.
“But if you look at the big picture I have scored 23 this season and I scored 21 last season so I have already done better than I did last season.
“And coming off a couple of goals against Falkirk, my confidence is sky high again so I am looking forward to Saturday, massively.”
The Scotland Under-21 player believes the Leith side are due some good fortune at Hampden Park which will allow them to silence their detractors.
In last season’s Scottish Cup semi-final they were the better side only to go down 1-0 to Falkirk and last month they bossed most of the League Cup final against Ross County before losing 2-1 to a last-gasp Alex Schalk goal.
“It seems that when we go to Hampden we just don’t seem to get the result, even if we are the better team,” said the former Hearts youth player.
“I think we are due a wee bit of luck and hopefully we can get that and break the Hampden curse.
“Everyone seems to say Hibs have bottled it in big games. I would love to go out on Saturday and just prove everyone wrong.”
As most Scottish football fans know, however, Hibs’ poor record in the Scottish Cup goes back further than last season.
The Edinburgh side last won the trophy in 1902 and Stubbs is looking for the chance to end that hoodoo.
He said: “We know the history and we know what the Scottish Cup means to this club and it would be nice to be the one to put the record straight.
“I would have thought there would have been a few Hibs managers in the past sitting saying the same thing.
“We have make sure we give ourselves an opportunity to be in that situation but first we have to overcome another Premiership opponent.”