Everything is simple here. Victories earn you points and lead to a promotion to a higher rank. Losses remove points and can lead to demotion. I advise you to always monitor the progress of each character right in the game. There is a rank bar that shows how far this fighter is from the next promo match and therefore the next Tekken 7 rank. You can read more about this here, which describes all the ranks and conditions for the transition from one to another.