With nearly two weeks of inactivity before the New York primary, and nearly a month since the last real contest of any size, candidates have had lots of time to campaign in this large state full of delegates.
Three candidates can claim some personal attachment to the State. Bernie Sanders was born and grew up in the Bronx. Hillary Clinton served as a Senator for about eight years. Donald Trump has lived and worked in New York for much of his life. Ted Cruz has no real attachment and has also incurred the wrath of New York voters by derisively accusing Trump of having "New York values" earlier in the campaign. Then, there is John Kasich. Is anyone even still talking about him?
New York is a proportional State for Republicans. This means all candidates will likely get some delegates based on performance. As a result, it is tough for the State to be a real game changer, but will continue the ongoing fistfight for every single delegate. The State holds a closed primary, meaning only Republicans can vote in the Republican primary and only Democrats can vote in their primary. Independents get to stay home. The time to change your party was six months ago, so "troublemakers" cannot cross party lines to vote, unless they planned far in advance.
Closed primaries have tended to favor Cruz over Trump. But that also tended to be in more doctrinaire Republican States or in such liberal States that Republican voters made up a small doctrinaire minority. New York has a thriving and relatively moderate Republican party, which has produced leaders that tend to be relatively liberal by Republican standards, e.g. Rudy Giuliani, Michael Bloomberg, and George Pataki.
For the Republicans, Trump has solid support in the State and is expected to win over 50% of the vote. It is an extremely weak State for Cruz, who may finish third behind Kasich. Cruz and Kasich both hope simply to minimize the number of delegates that Trump does get and move on to friendlier states. Trump his hoping for a stronger than expected win. Otherwise, he may go into the convention without the absolute majority he needs for a win on the first ballot.
On the Democratic side, Clinton remains the 10-15 point favorite over Sanders. Clinton remains on track to win a majority of delegates, despite Sanders' surprising support. Sanders currently would need to win more than 2/3 of all remaining delegates. Failure to win, and even a bare win in New York would not do much for Sanders' chances. Because Sanders has won a string of smaller State Caucuses, Clinton is counting on a solid win here to crush the spirits of the remaining Sanders supporters. It will be the end of the Sanders momentum story as the campaign swings into a bunch of other races in mid-Atlantic States the following week.
Therefore, expect New York to be relatively good news for both front-runners, Trump and Clinton. But still no knock out blows expected.