Does 12th marks matter anyhow(60% vs 90%)?

First let's talk about those who've got 90%,

Sure, it may help you get into a good professional college but getting into a good professional college does not does not ensure anything. It's the work you do, the amount of time you'll put in, in order to achieve what you really want, whether you're ready to make sacrifices, whether what you want to achieve is really what you want(Or are you doing it just because everyone else around you is doing it ?) and many other factors that actually matter.

Now those who've got 60%,

In an ideal world, marks don't matter at all. But as we all know, the world, especially India, is not ideal.
I'm going to be frank: yes, that's going to affect your life.
Your first hurdle will be getting into a good college, which, unless the college has an entrance examination based admission procedure, is almost impossible to get.
But I can also tell you this: You can still change your life if you want to. What's done is done. What's about to happen is, on the other hand, within your control.
Your marks do matter. But only as much as you let it. Go do something you love, friend.

For example:-
There are 2 ways to reach a destination(to fulfil your dream),
First get on a highway(Who scored 90% can go this way)

or go by a field,(it sure is risky but definitely not impossible,60% scorers have no other choice).