For gaming, upgrading from i5 3470 to i7 3770k is not worth it since current-gen games don't make much use of Hyperthreading on i7, on dual-cores i.e. i3 HT is beneficial.
But for editing purpose i7 3770k can be much helpful.
You can get i5 3570k and overclock it for 8-10% more performance than i5 3470, since you already have Z77 motherboard for overclocking.
Honestly, I wouldn't bother, i5 3470 is still a powerful chip and wouldn't bottleneck any single-GPU graphics card out there. Games tend to be more GPU bound, so upgrading your graphics card to something more powerful or SLI GTX 770 which will provide you with biggest performance boost.