A former claims manager for the N.J. Turnpike Authority admitted in federal court in Newark today that he hatched a scheme that led to the theft of more than $1.5 million from the authority and various insurance companies. With the help of representatives from two New Jersey-based insurance companies, 55-year-old Gerardo A. Blasi of Clifton said, he inflated the costs to repair damage motorists did to NJTA property.