The program did not initially allow remote TAs, but they started allowing it after a year or two. The latest data I’ve seen is that about 50-60% of the TAs are also OMSCS students and the rest are from the resident program in Atlanta. It was my experience that GT professors preferred to have a senior TA or head TA from campus (usually one of their PhD students), but they were comfortable letting most of the graders be remote. Some online TAs earn a reputation for being awesome and wind up as head TAs, and some profs don’t mind having fully remote teams, etc., but that’s the gist of it.