Deine Mariner is Samoa's only player ruled out for the rest of the Rugby League World Cup after injuring his hamstring on debut.
Payne Haas withdrew from Samoa's 40-man squad after finger surgery but remains eligible as an injury replacement because he was named in the extended squad.
Samoa is monitoring the 26-year-old's recovery, though a return would need approval from Haas and his new club, South Sydney.
"We're monitoring the situation with Payne, and we will have further discussions over the coming weeks," Gardner told The Daily Telegraph.
"Ultimately it would be up to Souths (Haas' new club) and Payne."
Gardner denied reports that Haas had spent time in Samoa's camp before the tournament.
Haas left Brisbane Broncos ahead of his first South Sydney season in 2027. He has moved to Sydney and is understood to have settled in Maroubra.
A World Cup appearance could boost Samoa, but South Sydney may be reluctant to risk its marquee recruit before the 2027 NRL season.
Wayne Bennett is set to make Haas a key figure in the Rabbitohs' forward pack, and the club wants him fit for the opening round.