The OctaneBench results posted by OTOY CEO Jules Urbach show that the A100 GPU is ~30% faster than the RTX 2080 Ti. However, the GA100 (and all of its versions featured in the RTX 3000 GPUs) is a cut-down version of the A100, so performance gains for the RTX 3080 Ti may only be around 25%. Urback notes that results were recorded without RTX on, so there could be some minor gains when the ray tracing cores are activated.
https://www.notebookcheck.net/First-tests-for-Nvidia-s-A100-Ampere-compute-GPU-offer-more-clues-regarding-the-expected-performance-of-the-high-end-RTX-3000-series.482873.0.html