O.C.G.A. § 21-2-217
(b) In determining a voter's qualification to register and vote, the registrars to whom such application is made shall consider, in addition to the applicant's expressed intent, any relevant circumstances determining the applicant's residence. The registrars taking such registration may consider the applicant's financial independence, business pursuits, employment, income sources, residence for income tax purposes, age, marital status, residence of parents, spouse, and children, if any, leaseholds, sites of personal and real property owned by the applicant, motor vehicle and other personal property registration, and other such factors that the registrars may reasonably deem necessary to determine the qualification of an applicant to vote in a primary or election. The decision of the registrars to whom such application is made shall be presumptive evidence of a person's residence for voting purposes.
And even if they are denied above, which likely won't happen unless someone moves to the state just to vote, as some GOPers and people right here have suggested, the article in this thread also says that-- "If the registrar cannot determine whether the applicant properly resides in Georgia, the rule directs them to process the application but mark it as challenged, and to initiate a hearing."