Which EC2 type supports nvidia optix6/7?

According to the NVidia website, the OptiX dependencies are: NVIDIA GeForce, Quadro and Tesla products with Maxwell and newer generation GPUs.

This announcement: https://aws.amazon.com/about-aws/whats-new/2020/01/aws-now-offers-nvidia-quadro-virtual-workstations-for-ec2-g4-instances-at-no-additional-cost/ states the G4 instance type are Quadro enabled. "These cores, in combination with Quadro vWS, support RTX-enabled applications, for real-time ray-traced rendering and interactive computer graphics."

You could also look at the newer G5 instance types. https://aws.amazon.com/blogs/aws/new-ec2-instances-g5-with-nvidia-a10g-tensor-core-gpus/