There is plenty of evidence to suggest Nick Curran is alive.
I don't know what many of the people on this thread are thinking, just because of the ice pick under the bed at the end of the first movie(!). Anyone stupid enough to think Catherine would ruin the entire web she had just spun, successfully pinning the murders on Beth, by killing Nick just days later... then they just missed everything this character is about and the games she plays.
There are two very big reasons in Basic Instinct 2, also, to believe Nick is alive.
1) Catherine tells Dr Glass about what they used to do, driving to murder scenes and then having sex. These events must be after those seen in Basic Instinct. We have no reason to believe what she's saying isn't true, especially as it's so explicit.
2) Dr Glass calls Phil Walker, the detective played by Denis Arndt in the first movie, and he tells Michael that he believes Catherine "killed Johnny Boz and two police officers". Those two are Marty Nilsen and Gus, NOT Nick Curran.
Surely if Nick had died under mysterious circumstances it would have been mentioned, at least by Phil Walker. If Nick was dead, it's highly unlikely it wouldn't have been mentioned at all. If he was dead, they would have said so. Until it's proven, he's still alive, and as I've pointed out, there's more than enough evidence to support it.
"Never underestimate the power of denial."
American Beauty