I've never made a pâté and have eaten it just twice. Both times, it tasted fine, but it wasn't something I'd go out of my way to eat again.
Terrines - I think I've only ever seen those twice as well, and not in person, but on cooking shows, and both were European cooks. Before that, I wouldn't have known what a terrine was, I'd never heard of one.
I always hate trying to answer for my entire country, because I'm sure there are plenty of places here where pâté is consumed, and I'd certainly heard of pâté, even as a child, but it was something we never ate, never saw it before, and my only exposure was through TV shows and books. Much like caviar, pâté was something rich people/city people/movie stars/sophisticated people ate, like on The Love Boat or Dynasty. Lump escargot in there as well.
I do know this - we rarely run across people who eat pâté, and if it's mentioned, we'll get the "oh, ick, you do know how they make that stuff, right?" MrsTasty has had more than one travel client mention that somewhere she sent them (cruise or all-inclusive) had pâté, "but there was no way we were trying that!"
Excepting veg* ones, I would guess that as animal cruelty awareness has risen, pâté consumption has gone the way of wearing fur - people still do it, but you might get a lecture about it.
I've never seen pâté on a menu in the US, and when we eat out, we frequent some fairly nice/spendy places, though admittedly, we rarely go to dedicated French restaurants.
Circling back to terrines - it occurs to me that I did grow up eating headcheese and sousemeat, and those must at least be related to terrines, so I'm off to do a little research on that. Depending on what I find, I may have to change my answer.
Circling back a second time, now to the pâté, we used to belong to a German culture club, and when we would go to parties there, like New Year's Eve, there'd be pâté. These weren't catered per se, the food was all made by the members. So I misspoke earlier - I have seen pâté here!