Four independent sources reveal that that the RX 6800 XT cards perform up to 19% better in the Firestrike tests, and up to 3% faster in the Time Spy tests, but still trail behind the RTX 3080 in the Port Royal tests that focus on ray tracing performance. One of the sources claims that the AMD cards can even beat the RTX 3090 in the Firestrike tests, but we are suspecting the source is actually confusing RX 6800 XT with the more potent RX 6900 XT in this case.
https://www.notebookcheck.net/Big-if-true-pictured-Radeon-RX-6800-XT-engineering-sample-is-beating-the-RTX-3080-in-almost-all-leaked-3DMark-results.498979.0.html