atmel studio for mac
No, recent versions of Atmel studio are based on Visual Studio which is Windows only.

You could run it in a virtual machine.

But it's worth noting that Atmel studio uses avr-gcc and arm-none-eabi-gcc (and presumably an avr32 gcc) to do the actual compilation, all of which are available for other platforms.  As are downloading tools for their bootloaders, and ISP and SWD/JTAG tools like avrdude, OpenOCD, etc.

Also the Atmel Software Framework of chip-specific source code libraries is available as a huge zip file download independent of Atmel studio.

GDB works well with an SWD adapter for Atmel's ARM parts, there are some indications it can be made to work with the AVRs connected via an Atmel ICE, but never personally tried that.

So unless you want to use a setup that's unique to Atmel parts, you can readily target their parts using your favorite work environment running on top of your favorite operating system.