Do keep in mind that multiplayer FPS is different from actual FPS you should be getting (in like singleplayer), since it's dependant on server hardware.
Putting view distance to around 2500 and object distance 1800 helped a lot, but I'm not sure my overclocked i7 2600K performs better in CPU bound situations than your newer gen i5 7600K.
Use this as a basis since I got a weaker system and up the settings until you're satisfied:
sampling: 100
Textures: Ultra (for you, I use Very High because of stutter)
Objects: Ultra (less pop-in)
Terrain: Low (it disables grass, but it hinders you more than it should in multiplayer. Otherwise go with Standard)
Shadows: Ultra (lower settings from standard and below use CPU, High and up use GPU)
Particles: Low (helps with smoke)
Cloud: Whatever you wish
PIP: Disabled (in-game mirrors, unless you really want to have it on: put it on Low)
visibility
Overall: 2500
Object: 1800
Shadow: 100 (200 is too intensive for my system for what it's worth)
lighting
HDR: Standard (lower that for FPS)
Dynamic Lights: (No idea how much this affects systems. Probably a lot at night, so tweak that yourself)
Water Reflections: Standard
With the tab of "AA & PP"
AO: Whatever you wish, your GPU is fine and even my GTX 770 can run HBAO+ Strong easily)
Caustics: Only is visible underwater but it's a nice effect to have on
Anti Aliasing: I have it set at 4x since that is acceptable performance for me, you might be able to run it at 8x
ATOC: All Trees + Grass
PPAA: SMAA Ultra
ANISO FILTERING: Ultra
If you use this preset test out your FPS in a location like Kavala, west of the island of Altis.
Throw a smoke grenade, drive a vehicle, go into the editor and use shift with the camera and fly by from Kavala to other regions to see if you get stutters. This might be VRAM (in my case, not yours probably) or HDD/RAM speed related.
RAM speed, hard drive speed (preferably SSD) also have an effect on performance.
If you still have troubles with FPS at these settings, raise the sampling slowly from 114% to 200%. If you hardly notice a performance decrease (or no FPS drop at all) it means your CPU is holding you back.
In that case overclocking will help drastically.
Your GPU is just fine for this game.