Would a takeoff be aborted if 'rotate' is not called out?
That could end up being a really bad idea if you've accelerated past your V1 speed -- your abort would then put you off the end of the runway, and the consequences from that range from bad to catastrophic.

A much better idea would be to look at the markers on your airspeed indicator, and if you're at/above rotation speed, go ahead and rotate.  Then sort out what's up with your copilot.

The worst case is, he's incapacitated, unconscious, experiencing a stroke or heart attack or something similar, and you'll probably end up returning to land as quickly as possible.  While the idea of staying on the ground to get him EMS help sooner might seem to be appealing, he'll probably NOT get better attention if your aircraft just ran off the runway, through the airport fence, and into whatever terrain/water/civilization lies beyond, because you didn't start your abort until several seconds after you should have been flying.  Better to come back and land with ONE sick person on the airplane, rather than crash, making your copilot now one of potentially MANY injured/scared/incapacitated people on a damaged jet -- and he with the very least ability of any of them to evacuate himself!

Or, maybe he got distracted and he's fine, and after he overcomes his embarrassment for missing the important callouts, the rest of the flight will go fine.

So, no, if the copilot doesn't call "V1, Rotate" I would NOT recommend aborting the takeoff.  If you see him slumped over when he should be making an "80 knots" or "airspeed alive" call, that might be a different decision; at that sort of speed you're in no danger of running off the runway &amp; you could probably taxi back to the gate promptly.  But if he's missed his calls at significantly higher speeds, aborting is a bad plan.