Tai does not know about Jason's idol, I believe. Only Jason, Scot, and Cydney know. And everyone knows about Tai's idol lol.
Although I'm not sure of the chances of the Super Idol happening because Tai voted for Jason this past Tribal. Idk why it was done, whether it was confusion, dislike, or trying to take the target off their backs. Either way, if Jason finds out that Tai voted for him, he'll be pissed. It's in Tai's best interest imo to pretend that Joe voted for Jason and Tai voted for Nick, although the chances of Tai lying are slim. However, I think the Super Idol benefits Scot and Jason much more than Tai.