get the new video card and you will see if you are satisfied with end result ,
if not only then upgrade your cpu to i7 4790/4790K depending on which motherboard you have
(if you don´t have "Z" chipset motherboard buying "K" cpu is pointless and waste of money)
well , gtx 1060 is just about right video card for your processor .
overall you will notice a performance boost with 1070Ti
but not overclocked haswell i5 will bottleneck it ,
especially in cpu intense games and multiplayer.
get the new video card and you will see if you are satisfied with end result ,
if not only then upgrade your cpu to i7 4790/4790K depending on which motherboard you have
(if you don´t have "Z" chipset motherboard buying "K" cpu is pointless and waste of money)