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.
The developer is not very competent. So it might not happen.