Clearly a male. Noticeable hemipenal bulge along with typical male coloration at that size.
On a side note. I cant stand when people sell beat up panthers like that. He is not overly beat up but you can tell he has been in contact with at least another animal from the marks on his one leg, side and chin. With the price these guys go for you would think a person could at least keep these animals separated enough not to have battle wounds already. Its not bad but still.