Television, at this time, was still in its relative infancy--but television sets were selling quickly. At the start of 1947, a few months before Robinson's debut as a Major League player, there were just 16,000 television sets in the country. A year later, there were 190,000. By the start of 1949, there were approximately one million sets in use--and by the beginning of 1950, at the time of the New Yorker article, there were some four million (in 9% of American homes). Sales, during 1950, were brisk. By January of 1951, there would be more than ten million sets in use (in nearly 24% of American homes).
Lastly, here is a piece about the subject of ballplayers and off-season jobs, from the website of The National Baseball Hall of Fame and Museum. It is by Lenny DiFranza, the Hall of Fame's assistant curator of new media.