Portugal's participation at the 2022 FIFA World Cup in Qatar rests on whether they can negotiate a play-off final against North Macedonia on Tuesday.
Ronaldo turned 37 last month and the upcoming tournament could prove to be his last if Portugal make it.
After Qatar, the next international tournament is EURO 2024 in Germany by which time the five-time Ballon D'or winner will be 39 years.
Ronaldo holds the record for most international goals in men's football with 115 goals in 185 appearances for Portugal, for whom he made his debut in 2003.
Ronaldo has played in four world cups and five European championships to date.
Ronaldo's nemesis, Lionel Messi, hinted last week that he could be drawing down the curtain on his international career after the world cup but the Manchester United forward maintains his future with the national team is undecided.
"I'm starting to see that many of you ask the same question," Ronaldo replied to reporters at Monday's pre-match press conference.
"I'm the one who's going to decide my future, nobody else.
"If I feel like playing more games, I'll play; if I don't feel like playing more, I don't play. I'm in charge, period."
Ronaldo added on Tuesday's opponents: "We know that they are a very well organised team." "They have their strengths.
"We respect them, but I think that if Portugal are at the best level, they will beat any team in the world.
"[It is the] game of our lives, too, not just for Macedonia. I hope the stadium can respond in the best way, with a very strong atmosphere throughout the 90 minutes."
Ronaldo led Portugal to glory in EURO 2016 and the inaugural edition of the UEFA Nations League in 2019.
