It's a pretty prestigious journal. It's likely that aides to senators and representatives in key positions, as well as it being forwarded from interested constituents will make sure that the article makes the rounds. And it's generally good political practice to keep informed on the moves made by major players. Likely people in the White House know about it as well.
When I say "read" I mean take the time to understand it and put thoughtful consideration into it. Repealing Obamacare is an idealogical imperative to most Republican legislators, it's intrinsic to their identity now. Awareness of what they probably consider propaganda is not the same as "reading" it.
While I appreciate the skepticism, and it is sad that there is an apparently increasing number of questionable journals out there, do you have any evidence that NEJM is one of them? They're currently run by the NEJM Group, which is controlled by the Massachusetts Medical Society.
They might not, but they are probably lobbied by doctors, hospital administrators, and insurance executives, all of whom are likely to at least skim the top medical journals.
A good chunk of the rich that foot the bill for a lot of the ACA subsidies[2], the same ones that pump money into PACs and would see money coming back into their pockets if the ACA was repealed [1], also have a vested interest in saying "meh, those journals are full of crap".
Our HMO we used at old job hated ACA. At least their representative told us that informally. Another doctor I know also does not like. Someone who is self-employed with a pre-existing condition really likes it. It was hard for them to get insurance before.
The US system certainly makes a lot of money for providers and insurances. Otherwise it would be cheaper. The money must be going somewhere. These people don't want change.
Some articles have suggested that ACA repeal poses an existential threat to rural hospitals and even the private healthcare industry, so those groups definitely care about remaining in business.