What FPS will I get in Eternal Return at 1440p?

At 1440p Ultra native, expect around 180 FPS. With DLSS Quality you can push higher.

Does GeForce RTX 4090 ROG STRIX LC GAMING OC support DLSS or FSR in Eternal Return?

Yes — Eternal Return supports dlss2, fsr2.

Yes — the GeForce RTX 4090 ROG STRIX LC GAMING OC runs Eternal Return at approximately 240 FPS at 1080p Ultra (native, no upscaling).

✓Yes — Excellent

Expected: 240 FPS @ 1080p Ultra (native). This GeForce RTX 4090 ROG STRIX LC GAMING OC is currently $3990.00 at Newegg ↗