Yes, The Interview is now available online (Google Play and You Tube for sure and possibly other sites) to rent or buy. However, at the moment this is only available to people in the USA.
Although the film can technically only be viewed by people in the US, there are ways of course, of tricking your server into believing that you live there. All you need is a VPN (Virtual Private Network) which acts as a shield and disguises your actual location.
There are many VPN service providers, but one that is free (although there is a paid version) and genuine is CyberGhost who are offering a 50% discount on their premium services before 10th January 2015.