I'm about 90% sure its a male. The trailers will likely start coming in within the next month or two. In my experience at this size many Rivulatus show their male vent. In this picture if you zoom in, you can clearly see the male vent halfway between the anal and pelvic fin.
Other traits that suggest male, are the elongated body shape, and the more sparce worming on the face. Though his orange trim is thin, he has a wonderful body shape. He will be a looker for sure.
Another thing to note, in my experience the black eyemark will stay visible til about 4-5.5". No one ever told me that when I first got one and I wondered how long it would be there. Another thing be VERY CAREFUL with feeding these guys. Two times a day, DO NOT try and power feed. Rivulatus are Hexamita magnets in my experience.
I actually have one growing out right now about this size in a 75g with a Flowerhorn, and quite surprisingly he's been beating the crap out of the flowerhorn. I might have to separate them earlier then I thought.