I think they need 60 votes to close debate. That's why Reid wanted an agreement to limit the length of debate, which the GOP refused. In fact, traditional filibuster was about talking non-stop during debate until the other side simply gave up or the session ran out and Congress adjourned. Yesterday's vote was actually to open debate.
That's why our own idiot Chris Murphy could babble on for four hours the other day about the Newtown shooting. There's no stop to how much political mileage he's gonna try to get out of that tragedy.
Then if the Senate does pass anything, it still has to go to the House, which is GOP dominated.
The real problem with the vote to open debate, which is what happened Thursday, is that it builds momentum for the anti-Second Amendment side, and momentum is always bad.
Having said all this, right now the prospect to defeat this bill entirely doesn't look too good. There's a lot of Mental Health stuff being put in this bill, and that stuff has bipartisan support. There's also things like universal recognition of state permits (every state will have to recognize any state's pistol permits), as well as looser provisions for the interstate transportation of weapons for hunting purposes, both of which are on the NRA wish list. Even if these latter provisions doesn't survive, the fact that things like it are floating out there in the Senate tells me there's enough GOP and red state Democrats out there looking for something they can take home.
Right now, 60 percent chance something with universal background checks in it will pass, IMHO.
Oh, by the way:
"As Senate Democrats struggle to build support for new gun control legislation, the American Civil Liberties Union now says it’s among those who have “serious concerns” about the bill...."