Goal-kicking might affect the decision, with Anscombe not adopting the role for his new club Gloucester.
Anscombe, 33, has not played for Wales since sustaining a serious groin injury before the World Cup victory against Georgia in October 2023.
“He [Anscombe] is not goal-kicking at the moment, so we need to see where he’s at in terms of that and how much he’s done,” said Gatland.
“Gloucester have a couple of good goal-kickers. Gareth is a good goal-kicker but he had that problem with his groin for a long time which kept him out.
“It’s just about seeing where Gareth is at this stage.”
Thomas, 25, was impressive in the summer with Wales as a goal-kicker but is not the first-choice for Cardiff in this department.
“It is about making sure he gets a volume of kicks,” said Gatland.
“I spoke to Matt Sherratt [Cardiff head coach] about how much he’d done.
“It’s important he gets up to speed and those players will be working hard.”
