Internet gambling in New Jersey has been underwhelming in the year since it began, and it is now under attack by opponents looking to shut it down, even as it provides a small bit of help to Atlantic City's struggling casinos. When Internet gambling was launched, it was hailed by many as a potential game-changer that would help reverse years of declining revenues at what were then Atlantic City's 12 casinos. Gov. Chris Christie's administration expected online betting to bring in $1 billion in its first year. But only one-tenth of that — just over $111 million — has materialized. Four casinos have closed and a fifth is poised to do so next month. And one Internet gambling company, Ultimate Gaming, left the market after an unsuccessful fling with the Trump Taj Mahal. But even the small revenue boost from online gambling is helping the casinos that offer it. In several months, Internet winnings were the difference between the surviving casinos posting a revenue decline or an increase compared with a year earlier.