With that kind of construction we use the bare infinitive:
How many people eat apples?
How many of you drink coffee?
How many of you want to come to my lecture?
How many teenagers take drugs?[/QUOTE]
I hope you don't mind my asking: do you really think it's a bare infinitive? I've always regarded it as present plural (as many would imply the presence of a plural subject), whereas with how much the third person present singular is used.
How much salt needs to be added?
How much more work has to be done?
How many students go home at the week-end?
Furthermore in past sentences, past tenses are used according to the subjects of the sentences.
How many students got an A?
How many bottles of wine were bought?
How much paint has been left over?
How many boxes were missing?