introducing 5-yr-old JRT male to female JRT puppy

Our 5-year-old JRT male, Jake, spent the first 3 years of his life with our elderly female lab. They were fine together; he curled up with her every night. Since Belle's death two years ago, Jake's been on his own. Two weeks ago we brought home Gracie, a female JRT puppy. Jake is very unhappy. We don't dare put the two of them on the floor together; we sense that would be the end of the puppy. How do we get Jake to accept her?