Despite the fact that even some of Samsung's own devices with just 512MB RAM run KitKat just fine, the company still claims the international Galaxy SIII's and SIII mini's 1GB of RAM is not enough to run KitKat.
In order to facilitate an effective upgrade on the Google platform, various hardware performances such as the memory (RAM, ROM, etc.), multi-tasking capabilities, and display must meet certain technical expectations. The Galaxy S3 and S3 mini 3G versions come equipped with 1GB RAM, which does not allow them to effectively support the platform upgrade. As a result of the Galaxy S3 and S3 mini 3G versions’ hardware limitation, they cannot effectively support the platform upgrade while continuing to provide the best consumer experience.
Do not buy Samsung phones.