Hey there Salmati,
Welcome to the Chromecast Community Forum! I'm sorry to say, but the Chromecast with Google TV is unable to provide Dolby Atmos through Bluetooth. Chromecast outputs surround sound if a particular app supports it, and if the Audio/Video Receiver (AVR) or TV it's plugged into tells the Chromecast over Extended Display Identification Data (EDID) that it supports 5.1, AC3*, and AC3/EAC3* surround sound. If the TV or AVR do not support one of these settings, Chromecast will not output surround sound.
I hope this answers your questions, and if you have any other questions or concerns for me, please let me know!