What class standing is sufficient to have high odds to get big law from NYU?

Top 2/3 of the class, and you will have a shot, though one would probably have to be around median to start feeling a bit safe. Big firms in NYC are the bread and butter of NYU hiring, and is generally considered a pretty easy and attainable goal for almost any NYU student with relatively decent grades. As a general proposition, if you want a big NYC firm out of NYU, you will likely get it.

If the recent statistics are anything to go by, you "have a shot" pretty much anywhere in the class except the very very bottom. And no-one outside the top 1/3 or so anywhere should start feeling a bit safe. Once you're out of V15 range and the 100+ person summer classes at those firms, luck becomes a much bigger factor. Not so much because firms don't want you for your grades, but because firms in that range are looking beyond grades and when they're hiring only 15-20 people they're sorting through a bunch of folks with relatively similar stats using non-grade criteria.

Wouldn't this apply to other schools in the T14?

As usual, everything Rayiner said is correct. Most everyone (but not everyone) in my class I know who wanted biglaw got it. Among those I know who struck out at OCI, their GPAs spanned a wide range from modestly above median to direly low.

Basically, there are some jobs that require very top-of-the-class grades. And, very few employers are looking to hire very bottom of the class. But if you fall in the great wide middle between those two extremes, grades become one of many factors that will effect your success at OCI.

This describes class of 2013 as well.

Note, though, that the corollary to "you can get biglaw from almost anywhere along the curve" is "you can fail to get biglaw from almost anywhere along the curve." There's no bright line where you're "safe," i.e., at a minimum you have to show up to interviews, act professional, carry a conversation, seem interested in the job, and so on. The bar is just significantly lower the better your grades are.