I haven't seen any benchmarks for GTAV on the PC yet. At 1440x900 a GTX770 should tear through anything. People competently play games like Battlefield 4 Multiplayer at 1080p with GTX750Ti and GTX760, so you should be fine.
GTX980 is a direct predecessor to the GTX680 and GTX770, whereas the GTX780, 780Ti, Titans are all based on a different architecture. There is some performance to be gained here, but nothing drastic.
I'm still running old GTX580 @ 1080p and haven't found a game I can't run with a pair of them. Consumes an awful lot of electricity in the process though. I have the rough GPU equivalent to a GTX780 in there, but with less memory.
Could save a little on the cooler, but that is a drop in the bucket. Memory and the CPUs are just a little pricey at the moment. Only been a few weeks since release. Even then a I5-3350p core compared to a Haswell - E core isn't a huge improvement. Maybe 15% IPC.
PCPartPicker part list:
http://pcpartpicker.com/p/HvxPvK
Price breakdown by merchant: http://pcpartpicker.com/p/HvxPvK/by_merchant/
CPU: Intel Core i7-5820K 3.3GHz 6-Core Processor ($384.99 @ NCIX US)
CPU Cooler: Phanteks PH-TC14PE_BK 78.1 CFM CPU Cooler ($74.99 @ Amazon)
Motherboard: ASRock X99 Extreme4 ATX LGA2011-3 Motherboard ($220.99 @ Newegg)
Memory: G.Skill Ripjaws Series 16GB (4 x 4GB) DDR4-2400 Memory ($259.99 @ Newegg)
Total: $940.96
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-09-18 16:16 EDT-0400