J Street released a poll that stated that Jews agree more with Obama than Netanyahu, but it is J Street that did the poll; therefore, I don’t believe it or anything else they say.
Yes, you can believe a J Street poll about as much as you can believe an article by Prof. Jonathan Gruber on Obamacare c. 2009-2010 or an oration by Ms. Debbie Wasserman-Schultz on anything.
BTW, in case you didn't notice, the article that began this thread came from a left-leaning publication, The Atlantic. It doesn't specifically say which poll they got their data on Jewish voting from. However, from the title "Are the Democrats Losing the Jews?", it would appear that they are at least a bit alarmed at the trend.