So the bottlenck will be your CPU, as it's not fast enough to give the GPU pre-rendered frames. The GPU is much stronger than the CPU you have, and this means your new GPU will always be waiting on your old CPU.
Maybe you could get a second hand GTX1080 or such. It's still quite strong at 1080p.
There is no such thing as "bottlenecking"
If, by that, you mean that upgrading a cpu or graphics card can
somehow lower your performance or FPS.
A better term might be limiting factor.
That is where adding more cpu or gpu becomes increasingly
You WILL do better with a gpu upgrade.
The question is by how much.
Try this simple test:
Run YOUR games, but lower your resolution and eye candy.
This makes the graphics card loaf a bit.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
If you are very cpu limited, only a platform change will bring a major upgrade.
In the mean time, if your motherboard is a Z prefix, you probably have 20% more cpu power available wit overclocking.
These are essentially the same thing, and the term most people will refer to. I would agree that people get hung up on the term 'Bottlenecking', (personally I despize it). Often they are confused about what the issue is.
However, in this instance, the 4th Gen Intel chip is not providing pre-rendered frames fast enough to such a GPU. The GPU will always be waiting on the CPU.
Change that to a Ryzen 5xxx/7xxx Intel 12th/13th Gen you will see big improvements. That's because the cpu sends the pre-rendered frames faster than the older CPU, unleashing more performance.
Someone actually tested the i7 4790k two years ago and found the comparably priced AMD GPUs to be way faster. Your 970 is similar in performance to the tested 1060 and you can see even the $80 RX580 is an upgrade