Had a tough time finding Gigas at all on The Island, Ragnarok and Valguero. Been a while since I played Ark but remembered we used to tame them on The Center so I went and tried there. 3 hours later I tamed a 130 and150 male. Granted I’m playing on SP but still I was doing the same on the other maps and found next to nothing for days. Don’t waste your time looking on any other map
If one is encountered near water, you can simply lure it out to sea with a flyer and it will swiftly drown. Given the water is deep enough. If encountered inland not near water. Pray to the overseers you have something fast enough to out run it. Then promptly die because they're as fast as a mad Hispanic mother with a shoe. Not as deadly as one though.