As far as I know, LPub can use either LDView or POV to generate it's images, and by default it uses LDView. So, the image quality should be the same (assuming you're not using POV; and if you're using POV, it should be better, but without edge lines, and really slow).
One thing you can do is create a preference set in LDView. I think you need to name it "LPub". If you have that preference set, LPub will (mostly) use the settings from that preference set. (I say mostly, because I think it forces certain settings, like edge lines.) So, you can then go into that preference set and enable things like antialiased lines. You can also make sure that "low quality studs" is disabled.
One thing you can do is create a preference set in LDView. I think you need to name it "LPub". If you have that preference set, LPub will (mostly) use the settings from that preference set. (I say mostly, because I think it forces certain settings, like edge lines.) So, you can then go into that preference set and enable things like antialiased lines. You can also make sure that "low quality studs" is disabled.