I'm assuming the rest of your title was 50-60 FPS. You shouldn't make your titles so long and include your question in the post, not the title 😉
A 780 Ti should have no problem driving 60 FPS on CS:GO at 1440p. It's a game based on a fairly old engine so you should be just fine. Worst case scenario, as long as you're using g-sync, you won't notice if the framerate dips to 40 (if it does) because of how well it eliminates tearing and stuttering.