Does Amazon Prime video support Dolby Vision on Apple TV?
As of now, it does not. Amazon Prime Video on Apple TV 4K will send HDR10 content, which can be converted to Dolby Vision on the Apple TV itself, or sent directly as HDR10 if the "match content" setting is enabled on your box. Amazon Prime on Apple TV also annoyingly streams 2.1 PCM audio instead of 5.1, though Amazon says this is temporary, and that Dolby Digital Plus audio is coming soon to Apple TV 4K. 

For full compatibility, take a look at the supported devices / formats page on Amazon's website: 

Compatible Amazon Video devices and the features available on each device.