Hi There, I'm not that expert in mining or not related to as I don't have that much money to buy powerful ASIC machines to mine bitcoins...
But, according to btcgpu.org Bitcoin Gold is for GPU miners.
and that can really mine a lot of money using GPU's right?
How much money they can make with AMD RX580 8GB? Seems like a noob type question but really interested to know... 
Who knows until it happens. It is being announced as equihash, so a computer could possibly handle it. It depends on many factors. The very fact that it is being put out there as a fork will give it some following and that could mean a lot of mining. The announcements seem to push people to trade and buy, but until that moment there is no telling what the diff will be, the value, or anything.