The display earned him Man of the Match award and a R100,000 prize, which he revealed will go to his mother.
The 26-year-old defender, signed from Richards Bay, delivered a career-defining display by scoring a stunning hat-trick and being involved in four of the five goals during the encounter at Chatsworth Stadium.
"I'm a mamma's boy. The money will go to mum, and then we will see what we can do as a family," Gcaba said after the match, Sportswire reported.
Gcaba opened the scoring in the 12th minute with a powerful header and later added two more goals in extra time to complete his first professional hat-trick.
The game's drama peaked in stoppage time when Gcaba conceded a controversial penalty, which Lebohang Nkaki converted to level the scores at 1-1.
However, Durban City quickly regained control. Just three minutes into extra time, Mfanafuthi Mkhize restored the lead with a spectacular bicycle kick.
Gcaba then combined with Katlego Maphathe before scoring his second goal in the 111th minute, followed by a towering header three minutes later to seal the 4-1 victory.
The win not only marked Durban City as the first team to reach the Carling Knockout quarter-finals in their debut campaign but also showcased Gcaba's remarkable growth, having scored only two goals in 13 appearances for Richards Bay.
"I scored three, I'm super happy. Even though I didn't expect to score so many goals in one match, I'm proud of the performance. The team also worked hard, and we believe we can go far in this cup," he concluded.