The 34-year-old New Zealander, who switched codes for the second time following last year's Rugby World Cup in Japan, converted to Islam in 2009.
Betfred have sponsored club rugby league competition Super League since 2017 and last year agreed a two-year contract extension.
"We're in discussions with Super League about this, but Sonny has been very clear in his stance on the matter," Hunter told the Daily Telegraph.
"I think Betfred will benefit by taking the position that we respect and honour the player's religious beliefs.
"In today's society there are some very sensitive issues but I think the sponsor can say 'yes, OK, we understand this. He's a big brand and big name but we get it'."
In 2017, Williams covered up a Bank of New Zealand (BNZ) logo on his Blues shirt.
It later emerged that he was exercising a "conscientious objection" clause in his contract, telling New Zealand Rugby he did not want to wear the logos of banks, alcohol brands or gambling sponsors.
He switched to union in 2008 and won back-to-back World Cups, earning 58 caps for the All Blacks.
Williams, who has also tried his hand at boxing, is likely to make his debut for Toronto on February 2 against Castleford Tigers.