Tony Dokoupil is pushing back. The “ CBS Evening News ” anchor, who has been under intense scrutiny since taking the role in early January, led the signature CBS newscast to an audience of a little more than 4 million during the five-day period ended May 22, according to Nielsen — the first time in weeks the show has captured that level of audience. The program also notched 605,000 viewers in the advertiser-favorite demographic of people between 25 and 54. The previous week’s “CBS Evening News”