Iorfa has been a key figure for the club since joining in January 2019, but suffered a hip injury in the recent League One game at home to Lincoln City. Gibson, who is on loan from Everton, picked up a muscular injury in the first half of his League One debut for the Owls, at home to Bolton Wanderers.
The news somewhat offsets what had been a positive week, with Massimo Luongo and George Byers returning from injury in the 4-0 Football League Trophy win at home to Harrogate Town, and defender Liam Palmer following Iorfa's lead earlier in the season by signing a new contract.
On Iorfa, manager Darren Moore revealed: "He picked up an injury in the Lincoln game. He picked up a hip injury and it will keep him out for some time. It is a bitter blow for us.
"Both he and Lewis Gibson will be out until the New Year."
It could end Gibson's Hillsborough career before it has really got started.
"We are still in discussions with Everton," confirmed Moore. "It is possible we are looking at the loan and if there is a possibility to extend it or we both come to an agreement and end the loan.
"He is back at Everton receiving treatment. He is making slow and steady progress. There are still ongoing discussions with him."
Like Gibson, Hutchinson also went off injured at half-time against Bolton. His muscle strain is taking longer than expected to heal, and Moore has said the centre-back or central midfielder will not feature in "the coming weeks".
"We have had a little setback with him in terms of his programme," he explained.
"Sam won't be risked over the next coming weeks.
"He has tried training but it has not worked out. It is controlling the situation rather than pushing and pushing. We have eased off a little with him."
Moore this week recalled defender Ciaran Brennan from his loan at Notts County, and has told the 21-year-old he must seize his chance.
"He must look at it as an opportunity to stake a claim," he said of the youngster who made four cup appearances last season, and has had two Football League Trophy outings either side of his four games with Conference side County.
"He is back with us and the squad. He has got to be looking to keep his performance levels high.
"He is not a young player, he is part of the squad challenging for a regular first-team place."
The Owls host Gillingham in League One on Saturday, and are at Plymouth Argyle for an FA Cup first-round replay on Tuesday.