One hour on live TV. So if you pause live TV it only has a 1 hour buffer. After that it will start playing and you will have a full hour to FF. If you pause a recorded show I don't know that there is a limit. I have hit pause and left for a few hours and when I came back the screen saver was on but the second I hit play the show resumed.
rastergrafx - I would like to go beyond BBs answer because you are asking about a loooong pause LIVE TV on the same TV (not moving to a different TV).
As BB says this usually works. Just be aware that the live buffer used to store a pause is very fragile & when it is gone it is gone. Say you pick up the remote to restart your show & accidentally hit a channel button. You have just cleared the buffer forever.
I believe the pause should ONLY be used for short pauses that you can risk loosing. It may take a little more effort, but you can easily get used to setting up a recording - Push chan up or down then down or up to clear the live buffer. Then hit record or info/record. It will start recording from that point. When you want to watch it play the recording. There may be some cases where you want to watch from the beginning or FF through your previous viewing. In that case, do not clear the buffer before recording & you will get all of the show that you have previously watched.
Not to say that pause is not good. But, if you ask the question, it must be important to you. This is an opportunity to change your habit to a bullet proof pause.