While the 1050's Pascal architecture is of course superior to the 750 Ti's Kepler, I'm not sure whether I'd spend money on that particular upgrade.
Look at the raw figures:
750 Ti: 640 unified Shaders (what NVIDIA calls "Cuda Cores"), Clock 1020/1085MHz, Memory 2GB on a 128-bit bus.
1050: 640 Cudas, Clock 1354/1455MHz, Memory 2GB on a 128-bit bus.
So, the difference is a superior architecture and a 30% increase in frequency (a/k/a calculation speed). The same number of "calcuĺators" (Cuda Cores), the same memory size and type on the same bus.
Worth spending approx. 130 bucks? To some people, sure, to others, not.
To me .... not.
I'd save up some more $$$ and get a GTX 1060 3GB. It's day and night, really, like I said before, the 1060 is in a totally different league.
130 bucks for a slight improvement versus 230 bucks for a huge, really huge, improvement is an easy choice for me ... even if I'd have to wait for 3 months to be able to afford it.
But that's me, others will surely have a different view
Cheers,
Gaius