From Seeking Alpha:
At around 2 billion downloads per month (25 billion per year), Apple makes $1.55 billion in gross margin per year,” Elephant Analytics writes. “Of course there are additional costs involved with maintaining the servers and building out additional App Store features, as well as customer service costs. However, it seems fair to say that Apple makes over $1 billion per year from third-party apps in the App Store even if all that is factored in.
That’s more profit than Amazon.