Starting with SQL Server Reporting 2008 Reporting Services (SSRS) was the removal of the Internet Information Services (IIS) dependency, so you do not need to install IIS on the machine that you will install SSRS. This only applies when you configure it in native mode. In integrated mode you have to install SharePoint Web Front-End (WFE) components on the SSRS machine and this means a dependency on IIS, but that’s the dependency SharePoint has on IIS, not SSRS.
SSRS 2012 in native mode will use http.sys (think of it as a mini IIS), and cannot be configured to use IIS. But that should not matter as they can be installed and run side by side if needed. A lot of IIS-Like settings are configured by Reporting Service Configuration Manager.
Everybody (Why Leave IIS?)
Say Goodbye to IIS, Say Hello to HTTP.SYS!
Install Reporting Services and Internet Information Services Side-by-Side