RTX 3080 review is out on Guru3D, and yes, it makes an FPS difference....

Not so much at 1080p or even 1440p, but if you plan on building a new 4K gaming rig *or* you have an older generation/lower tier in a newer build, you need to wait for the new RTX 3000 series GPUs. The first review of an ASUS TUF version of the RTX 3080. It completely wrecks the RTX 2080 Super at 4K, increasing FPS to 43 from 29. That is a massive historically unheard of 48% FPS boost in FS sim history just from the GPU. Even at 1080p and 1440p, the difference between say a GTX 1080 and RTX 3080 is significant. Kudos to Guru3D also for having MSFS as a new game (yes, it is a sim) benchmark in their hardware performance reviews!

https://www.guru3d.com/articles_pages/asus_geforce_rtx_3080_tuf_gaming_review,20.html

The GeForce 2080ti does run the sim at 4K smoothly. You will get a few more frames with the 3080, but not significant to visual smoothness. I have the RTX 2080ti that is running an LG 34” monitor (5K x 2K) and using my screen recording to capture at 4K to make videos. The sim is very smooth with frame rates in the mid 30’s when recording. Remember that screen recording also pulls from system resources. You can check my latest 4K video here to evaluate.