Your intelligent geko needs to reproduce
Intelligence is obtained in a species with mutations through evolution, not by making one single element livingindividual live longer (some turtles can live up to 200 years, more than any human does actually, and that doesn’t make the turtles more intelligent).
The
The process works like this: If your gekogecko is a little more intelligent than the other gekosgeckos, and that is an advantage in their current ecosystem, then the intelligent gekogecko will have more chances to reproduce and distribute its “intelligent genoma”genome” to its brood, so the intelligence can evolve IF it is an advantage for the species. But the intelligence of that gekogecko will not raise just by living longer.