Even though the comb is on the large side, it is not very red and I see no sign of wattles. I think this is probably a pullet. I had an Australorp chick that had me guessing and second guessing for 8 weeks, and HER comb was larger and she had significant wattles at 6 weeks.
Still, you won't know for sure for another week or two, but I think chances for a pullet are good.