In general, if a lawyer ask for a large sum in damages in a tort case does that mean he or she is confident in winning the case?

When you say "ask", do you mean in a settlement demand or in some court proceeding (e.g. a complaint, or a closing argument at trial,e tc.)   Either way, it means very little, if anything.  It might reflect a legitimate expecation as to what the case is worth, or it might be complete  b.s.  Anyone can ask for anything.  However, it might mean a little more if done in a court proceeding because Court rules require that a lawyer have a legitimate basis for what he/she represent in or to the court.