Incorrect. Nginx overtaking IIS was first seen here:

http://news.netcraft.com/archives/2012/01/03/january-2012-we...

Look at the graphs on that page. You'll see that Apache is still number 1 (as it has been for the past 16 years), still has by far the largest market share, and is still growing fast. Faster than Nginx if you look at total numbers.

Nginx's primary benefit is performance, gained from its event based request model. Guess what Apache 2.4 has... The same thing. The idea that Apache is dying is laughable.