Ndabayithethwa Ndlondlo netted a brace, while Monde Mpambaniso and Edgar Manaka weighed in with a goal apiece for a one-sided victory at the Dr Petrus Molemela Stadium.
Gallant's were subsequently paired with Golden Arrows in their semis as Richards Bay were drawn to face Orlando Pirates.
Arrows overcame TS Galaxy 2-1 in their quarter-final clash, while Pirates beat Magesi 2-1, as Richards Bay saw off Durban City 3-1.
All the dates, venues and kick-off times will be announced by the Premier League.
The full semi-final draw:
Golden Arrows vs Marumo Gallants
Richards Bay vs Orlando Pirates
Golden Arrows will look to break their scoring drought when they host Stellenbosch FC, while newly promoted Milford FC aim to continue their impressive league start when they face Polokwane City in Wednesday's Betway Premiership action.
The league action continues this Tuesday with three fixtures pitting all the top-flight teams that are currently placed between position ten and 16 of the table.
Kaizer Chiefs winger Asanele Velebayi has urged new signing Faiz Abrahams to remain calm and focused as he prepares to experience the demands that come with playing for one of South Africa's biggest clubs.
Stellenbosch FC youngster Quwan Plaatjies admits he is struggling to find the words to describe his emotions after making Premier Soccer League history with a stunning hat-trick on his top-flight debut.
