Under today's law, the claim is viable for as long as a person lives. The law used to require US presence as a condition of citizenship retention. The law that covers Ted does have a citizenship retention requirement, but that has since been removed.
The citizenship retention under the 1952 statute was: present in the US before age 23; immediately following US presence, maintain five years of continuous presence. The five years of continuous presence is tallied only between the ages of 14 and 28.
The citizenship retention under the 1934 statute was: present in the US 5 years before the age of 21, the 5 years need not be a continuous period.
What you don’t find with a child born in the USA is a requirement for anything before the age of anything. This is the argument of many who assert that this is citizenship by law rather than by birth. Even Bobby Jindal, who was conceived in India by Indian parents but birthed in the USA, has no residency or paperwork requirement to assert his US citizenship.
However, that’s really not the main issue for me with Cruz. The issue for me with Cruz is that a super-lawyer with Canadian birth certificate in hand did not know until age 43 that he had Canadian citizenship, and I discovered it by googling for an hour or two prior to Cruz ever having announced his discovery.
I don’t believe him.