Cork star Ciaran Sheehan scored 1-4 as Cork IT eased into the last eight.
Sheehan's goal in the 22nd minute, following nice interplay from Colin Lyons and Michael Vaughan, opened up a 1-5 to 0-1 lead for the hosts.
Cork IT had begun well, wing-forward Sheehan knocking over three excellent points and lively wing-back Peter Daly also on target.
GMIT were struggling to stick with their lively opponents, but points from Aidan Walsh and Darren Durkan gave the visitors some hope at the interval as they trailed by 1-5 to 0-3.
However, the change in wind direction at half-time benefited CIT and they pushed clear again early in the second half.
Frees from GMIT centre-forward John Ryan ensured that they never allowed the home team to get completely out of sight, but the CIT defence always looked in command and the away side never managed a sniff of the goal they needed to threaten a comeback.
Late points from Sheehan, Kevin Hallissey and sub Daragh Treacy ensured that CIT had eight points to spare at the end, earning them a trip to Athlone IT next week.
Scorers – Cork IT: C Sheehan 1-4, M Vaughan 0-3, K Hallissey 0-2 (0-1f), C Lyons, P Daly, D Treacy 0-1 each. GMIT: J Ryan 0-3f, A Walsh 0-2f, O Warde (0-1f), D Durkan 0-1 each.
CORK IT – A O'Donoghue; P Kilkenny, M Griffin, N Galvin; C Lyons, S O'Donoghue, P Daly; B O'Sullivan, J Walsh; C Sheehan, S Finn, D Leahy; K Hallissey, M Vaughan, P Joy. Subs: D Crowley for Finn (h-t), D Treacy for O'Sullivan, E Byrne for Kilkenny (both 55), B O'Regan for Leahy (59).
GMIT – P Mannion; M Kelly, A McCormack, B Sheridan; C Sweeney, J Duane, R Shanahan; S Bohan, S Boyle; D Durkan, J Ryan, E Monahan; O Warde, A Walsh, C Kelly. Subs: T Costello for Bohan (h-t), S Tighe for Boyle (41).
Ref – M Meade (Limerick).