As far as higher resolutions go, in games limited by graphics performance (playing the most graphically-demanding titles at max settings), a 2080 Ti can be up to around 30% faster than a 2080. At 1080p, or at reduced settings, or in less demanding games like most esports titles, the performance difference will rarely get that high though, as the CPU will typically be what's limiting frame rates.
It's probably worth at least waiting to see what kind of performance you get on the new screen first, to decide whether more performance is desired, as a 2080 should be rather good at 1440p. And at this point, it might be worth holding out on an upgrade until later in the year, since it sounds like Nvidia will likely be launching a new...