The best thing you can do is run as far down the platform as you can (in the opposite direction from where the train enters the station) and wave your arms frantically to get the train operator and passenger's attention. Believe me, the passengers WILL be doing the exact same thing, as nobody wants to see you get run over and their train get delayed. If you can get to the far end of the platform, it gives the train more room to stop, and there is a ladder at the end of each platform where you can climb back up -- do NOT try to climb up from where you are. So many people have been killed trying to jump back up rather than getting away from the entrance end of the station.
that man could still stand, so at least he could walk or jog a little. with 60-80 seconds time before he got hit, he could move at least some good distance out of fear, that alone would buy himself priceless time and more attention.