I have just started taking multi vitamins, I bought Centruim but I realized it had no Hechsher. I asked my Rabeim one said since it is not Ochel you do not need a Hechser but my other rebbi said you do need a Hecsher (the multi vitamin centruim does contain gelatin). What is the right Psak?

If prescribed by a doctor – you can take it, since it's not edible. If you are healthy, and the vitamins are taken without a medical need, it's better to have a Hechsher. For Centrum – I heard a reliable source that quoted Rav Eliashiv that you can take it.