How many cups is in 23 oz?

Depends what you're measuring - not all ingredients have the same weight per volume, so when converting them into cups you need to take this into account. For example, 23 oz of chocolate mousse will require far more cups than, say, 23oz of lead cookery weights will require, since they both have different densities. This is why weight units cannot easily be converted into volume units, without stating the substance you wish to convert.