Gears "popularized" cover and survival mode and therefore did influence other games. I'm not getting into arguments about who had stuff first as anyone with a fair knowledge of games history will know few of the mechanics of Gears were original. What Epic did was polish, blend and meld a mix of proven and less proven mechanics and made them popular.
All popular games influence other games. For example the critical success of Uncharted 2 in terms of SP narrative and writing clearly influenced the improvements in Gears 3 SP narrative.
Most games are trying to be popular, and they therefore happily crib for any other source or title.
I doubt Gears influenced Uncharted directly though, they were both too far into development for that and early on it was clear both would feature cover based shooting, but the "vibe" of Gears visible during development coupled with the success of Halo and similar titles clearly influenced Sony's desire to have games that were less whimsical and more grounded, and this obviously had an impact on Uncharted's tone for example.
Gameplay wise though they are clearly different and I doubt for example Uncharted has cover based shooting because Gears did.
Try to be reasonable... its easier than you think...
