https://www.help.tinder.com/hc/en-us/articles/7606685697037-Powering-Tinder-The-Method-Behind-Our-Matching

they mention they don't use "Elo" but that doesnt tell us anything. competitive video games dont use "Elo", they use a proprietary algorithm that functions similarly to Elo. from the information on this link, it seems they use swipe data to determine who you see and who sees you (analogous to Elo) but they also use data from ur pics and bio to run through a matching algorithm (Gale-Shapley). its not as rigid as Elo and probably doesnt have discrete "ranks", but it has Elo-like properties