Yes, you can take MARTA to Cumberland Mall and also have access to the Cobb Energy Performing Arts Centre. It is an easy commute, though a long one.
Take MARTA to the Midtown Station and transfer to bus 12. After traveling through the west side and parts of Buckhead/Collier Hills, the bus ends at Cumberland Mall. You can also take the Cobb Community Transit (CCT) bus 10 from the Arts Center Station.
The buses end up at a transfer center behind Cumberland Mall on Cumberland Blvd. See the area map for information on the proximity to the Cobb Galleria.