Going to give as much factual info as possible, and attempt to answer every question as best I can.
1. Yes I do mean pascal. Though AMD also has cards coming out this year meant to compete with pascal.
2. It may very well be that the TI version is more expensive. But that won't matter I will address that later, please keep reading.
3. Optimistic release date for pascal is april google it and set search filter to last month. But here is one source.
http://techfrag.com/2016/01/25/nvidia-2014-2017-gpu-roadmap-pascal-titan-gp100-to-debut-in-april-gtx-1080-in-june-and-volta-in-2017/
Pessimistic release date -- August 2016 at the latest. It will either be Quarter 2 or Quarter 4 start as that historically is when ALL new gaming tech get released. So even if you only wait 2 more months you will be at an advantage with lots more new tech to choose from, even if pascal is delayed.
4. How powerful... While I can not say. I can say what happened last time 780ti - 980GTX (not ti just GTX 980) -- Total time between cards -- 315 days. The 780ti launched in nov 2013, the 980gtx in sept 2014. --- The 980GTX alone beats the 780ti in benchmarks. Check google and watch a video video's and you will see for yourself. This is important because the launch price of GTX cards is less then GTX TI cards. Meaning you can get a better card for less money. If your too lazy to look it up on google here is a video of performance comparison, but there are TONS of them out there.
https://www.youtube.com/watch?v=QZxpljkrsm8 --- Oh and that video... It is 970GTX to 780ti -- 970 wins. 980 wins by a lot more.
Further it has been 257 days since the 980ti launched, almost exactly halfway through 516 days as of today that the 9xx series launched. By the time pascal launches if it is in april it will have been 317 days. Do you see the trend? Unless moore's law has slowed down, or the last several series of cards power increase curve as it relates directly to days since last release is changing you can expect a xx80gtx in the next series will be as good or better than a 980TI today. It will also be cheaper if the historical trend remains for GTX vs dual GPU cards going all the way back to the X2 in the 2xx series.
---- Bottom line. Your money will be better spent on a XX80 GTX in the next series and possibly even a xx70 GTX, then a 980TI today. Less money for more performance if historical trends hold.
I am very sorry for another long post. I shortened it as much as I could.
Note: calculated release dates using wiki and a calendar calculator. You can go through all of the last 10 release if you want, but the trend will hold for performance increase per day between releases. It is a pretty linear path.