Can I legally carry a blank firing gun in Georgia ?

Sure, why not? There would need to be a specific law as applies to you and your personal qualifications and the type of possible "gun" you mention in order to restrict it.  Is it a dangerous weapon? Sure is (blanks can still kill or maim). Does it LOOK like a functional firearm? (Not all blank guns are equal.)  Are you a convicted felon?  Did you start by trying to look up the laws in Georgia that restrict carrying of dangerous weapons, or just expect us to do that for you?

The clinical term for carrying something that LOOKS like a gun to a gunfight is SUICIDE.

When you get shot for carrying an "almost gun" they will put you in for a Darwin Award!

Not in the presence of elected officials, or in polling places.  

You would carry a blank firing gun in the same manner that you would a real firearm if the blank gun cannot possibly fire a projectile it's not considered a weapon.

However that's not going to stop either the police or a thief or mugger from responding to you as if you were armed with a gun! And if you are a felon you definitely do not want to carry a blank gun because they're going to try to say that it is a firearm even if it cannot fire a projectile.

Yes, and you can legally fire a handgun, rifle or shotgun in Georgia if you are of age.

"Yeah, sure." - Nicolas Cage after reading ANY screenplay