Well, it”s not as simple as “family sponsorship”. Yes the wife can file, but whether that leads to a green card depends on a number of things. If he wants to adjust status as the spouse of a LPR, he will need to have been inspected and admitted into the US (that is, formally gone through a border post) and never been out of status while in the US. Did he enter legally, what is his actual current status and has he always been in status? If he has been out of status at some stage he would need to wait until his wife is a citizen, when as a spouse of USC he would be forgiven for having been out of status. However if he entered illegally he can’t adjust, regardless if wife becomes a citizen.