The 29-year-old, who was a key part of the World Cup winning team in 2019, was initially ruled out of the tournament with a calf injury sustained in the summer.
He only returned to competitive action a week ago with his new club Leicester before being called up as a replacement for injured hooker Malcolm Marx.
He did not feature in Saturday's 13-8 defeat by Ireland but the failure of South Africa's two goalkickers Manie Libbok and scrum-half Faf de Klerk has increased the calls for Pollard's return.
"Let's give Handre a chance to find his rhythm and see how he does with the other stuff," Erasmus said in a statement.
"Tonga will be a great yardstick to see how he goes.”
Erasmus, however, called for caution about expecting too much from Pollard as he tries to gear up to match readiness.
"Everyone must keep it in perspective," said Erasmus.
"Handre Pollard is not Superman and can't come back as fully ready after playing only 30 minutes of rugby since his injury.
"He can't just come onto the field to kick goals. He must also be able to sidestep, hand-off, make tackles, clean out at the ruck and that's obviously not the case now because he has only had a full week's training with us."
In spite of his exciting performances with ball in hand, concerns have been raised about Libbok's goalkicking.
He missed three penalties against Scotland in the first match and also failed with a conversion and a penalty against Ireland on Saturday,
"Manie is definitely playing brilliant fly-half rugby at this stage but obviously his goalkicking isn't matching that," said Erasmus.
"If you weigh up the different things he does, he makes a great contribution to the team but he is in a bit of a dip with his goalkicking.
"He knows it, we know it and the world knows it.”
Four years ago, Pollard scored 25 points across the quarter-final against Japan and the semi-final against Wales before scoring 22 as South Africa beat England 32-12 in the final.
