It means nothing. It is common in civil cases for Plaintiffs to ask for "the moon," or some ridiculous amount knowing that they will be awarded much less, if they should prevail. Also, the billion dollar figure is also being used, as is common in such court cases, to intimidate defendants (in this case Echostar/Dish) into thinking that they had better give themselves up to a royal F'ing and settle at Tivo's terms that would be a lot less than a billion dollars. Of course, Dish knows, as well as Tivo, that Tivo will never get anywhere near that award should Tivo prevail. In other words, it is all just part of the game.
As for your suggestion for Dish to purchase Tivo: Tivo wants too much money. Fighting the lawsuit really is much less expensive than buying Tivo (or agreeing to Tivo's terms of use of their patents: making the other party pay for just about ALL EXPENSES--marketing et al. while Tivo spends almost nothing). Now, if Tivo were really interested in Dish being a major investor in Tivo, a small percentage of ownership, or a seat on the board at Tivo, deals can be made at discount prices. However, I don't think Tivo wants Dish's investment; they want Dish's, and everyone else's, expensive monthly royalty payment. So, unless Dish and Tivo have been kissing in the closet, there will be no sale of Tivo (nobody wants to buy them, anyway; they are on life support, now) and certainly not Dish as a buyer. While almost anything is possible, things would have to change a lot for that to happen.