Does caffeine help keep the person aware of how intoxicated he or she is?

No. Caffeine does nothing to help a person be aware of how intoxicated he or she is. At most, it will keep them awake when they would otherwise pass out from alcohol intoxication. In that respect, it might make them LESS aware of how intoxicated they are by giving them a distorted perception of being less drunk just because they are a bit more alert.