Head coach Muliagatele Brian Lima had selected 12 local players to contest this weekend's repechage, but Tipa Sapeti failed to recover from an injury sustained in a practice match during the week.
Tuatagaloa is the only survivor from the Samoan team that was beaten by Spain in the Olympic repechage final five years ago, when Lima was the assistant coach.
"He knows exactly what happened and also he motivates some of these (other) players and we don't want it to happen again this year."
Five of the Samoan players were still in high school during the last Olympic repechage, but Lima said the whole team was determined to put things right.
"Some of the boys here I think they watched that game five years ago and the team is still hurting, and even the country as well, for not making that Olympics five years ago.
"We came here with the aim that we want to go to the Olympics, we want to qualify. I think that's the aim for this year."
A number of New Zealand-based sevens stars were not selected for Monaco because of the lack of quarantine places available on their return.
Tuatagaloa plays for Rouen Normandie in the French second division and joined the Samoan squad last week.
But Lima is confident in his local players and said he trusts them to perform.
"We only selected the best local players and we've been training for a long time and we prepare really really well physically and mentally for this tournament," he said.
"I think the boys they are looking forward for their first tournament of this year 2021 since the 2019 tournaments (in Dubai and Cape Town)."
Nine teams are left in the men's draw after Uganda withdrew, with France shaping as the biggest threat in the top four playoffs if Samoa can get out of their pool.
"We don't take any team lightly, we take all teams seriously, we take one team at a time," Lima explained.
"I think Tonga and Ireland are the teams to beat in our pool games and they are really tough - especially the high profile players that have been selected for their teams."
The Samoa women's team also kick off their quest to qualify for Tokyo later tonight.
The Manusina, who have also selected a locally-based squad, face World Series regulars Russia and Argentina on day one, before rounding out pool play against Mexico on Sunday.
Three of the four teams in Pool A will progress to the quarter finals, alongside two teams from Pools B and, with two Olympic qualifying spots up for grabs.