What do you mean by rival? because the only areas it really could rival gears is graphics and the way it tells its story (story itself might be another cheesy hollywood rip-off).
As for everything else (gameplay, sales, critical acclaim) I think it'll fall well short.
That's not to say it'll be a bad game, but it's gameplay is very "me too" and it doesn't have the rewarding feeling of taking down an intelligent AI like gears does. As for sales, well, Gears is a monster. Critical acclaim, I think Uncharted 1 was panned because of the copy-cat nature of almost everything about the game, hopefully Uncharted 2 will yield at least a more interesting and unique plot.







