Gestede was thrown on by Remi Garde on the hour mark and the target-man made a big impact.
The former Blackburn Rovers striker’s physicality proved to be a threat to the Newcastle defence, and he helped change the pattern of the match.
McClaren said: "After the break they grew into the game and I thought it could have been one of those days. Gestede made a difference.
"He caused us problems when he came on but after the goal we recovered and I think we finished strongly."
Prior to Gestede’s introduction, Newcastle had been on top, but Villa showed some excellent fight with the powerful forward on the pitch.
Garde’s side battled back to claim a point in the fixture, with Jordan Ayew netting a belter to ensure his side were not handed yet another damaging defeat.
Gestede was brought on as the awful conditions at St. James’ Park made it very difficult to play passing football.
With a target to hit up front, Villa could go long and Gestede did well at bringing others in to play.
He could actually have won the match for his side late on, but he tried to direct a header back towards a teammate rather than going for goal himself.
Despite the spirited display, the draw on Tyneside does little for Villa’s survival chances, as they are now 10 points away from safety and without a win in their last 16 league matches.