What monitor do you have, and what settings do you plan on gaming? Also, what future games do you intend on playing?
Upgrading to an i7 4790 won't have a difference, that's for sure, since you'll bottlenecked by both the CPUs. 4 cores, with or without hyperthreading is not enough for today's titles. For older titles, with video settings cranked up, there'll be absolutely no difference between the 2 CPUs. So you can drop the CPU upgrade to save some bucks.
For the GPU, the 1660 Super is better for sure. But you'll also have to keep in mind if you'd really benefit from extra performance by spending more. The 1060 is a capable GPU, and can run today's titles at low settings, or even med. So you won't go wrong with either GPU