Kittāvatā literally means “to what extent”, or more idiomatically “how is it defined”.
In SN 12.51 the question is:
Kittāvatā nu kho, bhikkhave, bhikkhu parivīmaṁsamāno parivīmaṁseyya sabbaso sammā dukkhakkhayāya
Literally:
To what extent, mendicants, would an inquiring bhikkhu inquire for the complete ending of suffering?
The question is not “how do they inquire?” It is, “how do you define the level of inquiry that is sufficient for the complete ending of suffering?” In other words, “Of those mendicants who are inquiring, how do you define one who is inquiring for the end of suffering?”
I’m sure I could phrase the translation better, but that’s what the sense is.