Sadly my brother-in-law passed away. He kept many things and among them was a coin / bill collection passed down from his father. One of the bills indicates it is a confederate bill but I'm not sure if it is real.
This would probably be better asked at r/numismatics.
That said, no, I don't think it is. The design looks like a 1861 $50 bill, but it should be much more detailed. It should also be multicolored, black and green.