Unable to start event gateway instance: Event Gateway Service is not enabled

@AXcrystallis were you able to resolve this issue ?
I am facing same issue, would appreciate your help

Let's see what's happeining inside the ColdFusion engine. To do so:

1) Ensure that 

"Enable ColdFusion Event Gateway Services" is checked (enabled)

2) Create a CFM page containing the following code, and launch it in the browser:

<cfset adminObj = new cfide.adminapi.administrator().login("your_cf_admin_password")>
<cfset gatewayObj= new cfide.adminapi.eventgateway()>

<p>
<cfoutput>Is the gateway service enabled? #gatewayObj.getGatewayServiceStatus()#</cfoutput>
</p>

What do you get?

One quick first thought is to make sure you've checked ALL the cf logs, right after getting that error. Perhaps there's more detail in one of them, rather than the one you quoted. Consider especially the exception.log, as well as the coldfusion-error and - out.log files. (And if on Windows, don't trust the date/time modified. I've seen that often not reflect recent changes.) 

But I have another idea beyond that. You don't quote the other resources discussing this, but it's clear you've read some give some of the info you share (and good for you).

One thing others have suggested for this--which you DON'T indicate--is trying to turn OFF that "Enable ColdFusion Event Gateway Services", and submit that page, then turn it back on and submit that change.

No, it's not obvious that doing this would help, but it did help someone (it seems, from my reading just now), and it would NOT be the first time such an unexpected change would suddenly make a feature "take effect". My sense in such cases is that sometimes some xml element in the associated neo*.xml file has a bad value, and "changing" it this way corrects that. This can happen especially if the settings were migrated from a previous cf version. 

Try it, at least (if you've not already)--and even if you did not migrate the settings.

And if you might, please consider saving off the neo-*. xml files in your instances lib folder (like cfusion/lib). Then after making the change you could identify what one changed and how it differed. (I find Beyond Compare great for that task, using its available "xml sorted" extension, that makes those nasty xml files much easier to compare.) 

Please let us know what you find or do, or if you (or others) find a better answer.