I'd hope not. He can be much better. Firmino is more of a creator while Martial can do it all both scoring and creating.
I've wanted Martial to play as a False 9 for ages now behind Rashford & Greenwood who play in a wider partnership like Yorke and Cole or maybe like Ronaldo & Bale would have if they played as forwards together.
Martial doesn't need to play like Firminho because ultimately Martial can score much more goals than Firminho whilst Firminho can pass a bit more cleanly. The player he should actually play like is Lionel Messi when he played as a false 9.
And no, I'm not rating martial as some second coming as Messi because martial will never reach his level of quality and no other player will but martial has the ability to play from deep whilst Rashford & Greenwood create spaces around for him to really mess up the defenders the way Messi would mess up the centre of defence by straight dribbling at them or trying to make some passes.
Martial has a good dribbling ability, can pick out runs, can finish off moves and can inter link the attack whilst also holding on to the ball. If he starts learning to play from the deep now, he will slowly start getting better at making cutting edge passes as a CAM/CF & then all of a sudden martial will look like a more complete player who makes the players around him play better as well.
Martial is our false 9, a forward who can play the furthest forward but also drop very deep to take on the defenders or play the ball to other attackers - but this requires Rashford & Greenwood to play as wider CF's like David Villa & Pedro used to play but probably even a little bit more closer together.
