@Emoryal why am I having to teach you about concepts that you're supposedly using to argue against me??
Using the following formula for deflection of light by gravitational lensing:
theta = 4GM/rc2
Light passing tangentially to Earth's surface should be deflected by 0.16 millionths of a degree by gravity.
if the earth were to maintain the same volume, but increase (or decrease) its density by 50%, would that significantly impact the amount of sunlight striking the earth?
No, the amount of deflection would still be basically nothing.
I'm assuming that our gravity has enough pull on light from our sun that at least some light that would otherwise miss us ends up getting curved just enough to hit us. Is this right?
Technically right, but it's a tiny amount. The amount of illumination from the scattering of light in the atmosphere is orders of magnitude more than from any gravitational effects.