NiceHash payout change constantly. People must remember, NiceHash is a marketplace... they can only BUY your hash power at a price they can SELL your hash rate at...
$21 per day? It is unrealistic. Don't expect to get more than $2 per card per day. I don't use nicehash but rather my own private miner switcher to mine the most profitable coin at any given moment of time and I have $3 per card per day for 1070.