Does his gears and suit give him that much power or how one's body can take so much G w/o hinch?
Yes and no, there's a bit of suspension of disbelief needed even for the iron man suit, just because you have a layer of metal around you, doesn't mean kinetic energy impacting it just stops, it will go through it and turn you into mush.
Like the first iron man movie where tony gets shot out of the sky by the tank, it was said it wasn't an actual tank shell that hit him, but some kind of secondary barrel, but even then his skull should've been fractured because he took it on the face and he lost no forward momentum, and then he crashed hard enough to leave a crater...
If it was an actual tank shell it should've gone straight through the helmet or at least turned tony into paste inside.
But there is where they use the standard sci-fi trope of "inertial dampers", these use vibrations to offset/disperse the energy so that the final effect would is minimised on the person, this is also the argument used for why rhodes broke his back when he crashed war machine; the power supply was damaged so the "dampers" were offline too.
Enter vibranium, this fantastical material is
wholly an inertial damper by itself, and an extremely effective one at that. There's a scene in civil war or black panther that shows this where black panther gets shot by regular caliber bullets, and instead of bouncing or ricocheting they
drop straight down having lost all kinetic energy on impact.
And remember this?:
Instead of turning cap into paste, or at the very least pulverised his arm, all the energy was dispersed at the point of impact instead of heading forward, causing the blowback leveling the surrounding area.
Or this:
Instead of breaking every bone in his body and possibly dying on the spot, the vibranium made it a minor inconvenience, remember he casually takes down a quinjet with all kinds of flips right after this.
Sam has the shield + the upgraded vibranium that absorbs the energy instead of dispersing it, and the suit itself probably has, either woven vibranium, or like the scale mail vibranium steve wore in endgame; unless you're thor or hulk level you're not getting through, which the movie showed pretty well imo, Sam gets hit, gets pushed back quite a bit and the wings are immediately at energy capacity while vibrating violently, followed by sam saying "oh god".
So no obviously something exotic like inertial dampers don't exist and all the heroes relying on some metal shielding should've been turned to paste on numerous occasions, but because it does exist in this fictional world, sam surviving while running away/avoiding a direct fight checks out.