Now the RX 470 8GB makes an average of $2.50-$3 or so. Most of it is due to the huge transactions fees for ETH transactions. There were times in the last 24 hours when the average transaction was 500 Gwei, while the average is normally 50 Gwei or so.
So when the hype ends in a day or so the fees will be back down and revenue will be maybe $1.50/gpu/day. While in 2018 if I recall most of the profits were in the miner reward of 5 ETH per block and not much was based on ETH transaction fees.
Either way, profits are as good as they were since middle of 2018 so can't complain.