The centre pairing recently clashed in the NRL elimination final between Gagai's Knights and Mitchell's South Sydney and, pending selection, round two is now pencilled in for Thursday, October 15, at Allianz Stadium.
Ahead of Sunday's NRL grand final, the International Rugby League (IRL) announced it had approved an application by Gagai to change Tier 1 eligibility from the Kangaroos to the Kiwis.
He was a member of the Australian team that won the 2017 Rugby League World Cup, and played the last of his seven Tests in 2018.
Playing for the Maori All Stars since 2019, Gagai qualifies for New Zealand through his mother Tania.
Under IRL eligibility rules, players who represent a Tier 1 nation - Australia, England and New Zealand - are unable to play for another Tier 1 nation.
Gagai's application was initially rejected on those grounds.
However, the IRL recently permitted Kalyn Ponga to switch his international allegiances to New Zealand and AJ Brimson to play for England after both had represented Australia at the IRL World Cup Nines in 2019.
Changes to State of Origin eligibility rules also enabled Briton Nikora, Casey McLean and Addin Fonua-Blake to play in this year's series despite not being eligible for Australia as they have represented New Zealand.
An IRL appeals committee accepted that Gagai, who has played 23 State of Origins for Queensland, had not been afforded the same option.
IRL chair Troy Grant said there were "special circumstances" in Gagai's case.
He said ARLC executive chairman Peter V'landys and Kangaroos coach Kevin Walters supported Gagai's application.
"Dane hasn't played for Australia for eight years and we didn't want him to be disadvantaged compared to other players with recent rule changes," Grant said.
"Dane wrote to us and Peter V'landys was very supportive - he felt there should be a bit of an amnesty period because we didn't want one player disadvantaged over another, given that Dane wasn't in the Kangaroos squad and it has been so long since he has played at international level.
"Dane didn't have the same option as other players who can play State of Origin and represent their heritage.
"It was felt that there were special circumstances in his case, so Dane is now available for selection by New Zealand, and it is now up to them whether they pick him."
The IRL appeals committee also approved an application for Kaiyah Atai to play for New Zealand after representing Cook Islands in World Cup qualifying in 2024 .
