Do ashkenazim drink the fifth wine glass on the Passover seder night?
The fifth wine glass is not drunk on Pesach night, and it is rather left symbolically as the cup still to be drunk at the time of our redemption.
Although some authorities (such as the Rambam) write that one should drink a fifth cup, this cup is not drunk in deference to the opinions that it is forbidden to drink a beverage (other than water) beyond the four cups.
According to some Rishonim, the Gemara (Pesachim 118) instructs the pouring (and drinking) of the fifth cup (see Ran, who cites both opinions); see also Maharal in Gevuros Hashem who writes that the drinking of a fifth cup is a virtue (segulah) for parnassah. The Levush (481) writes that this fifth cup represents the final redemption Geulah.
However, because according to many it is forbidden to drink a fifth cup of wine, the almost universal custom is to pour the fifth cup, and recite Hallel over it, but not to drink it.
Even according to the Rambam (Chametz Umatzah 8:10), the fifth cup is not on the same level of obligation as the other four cups.