I am seeing about 20% less sessions in google analytics compared to revcontent clicks.. is that normal?
i need 20% profit just to cover this difference.. any one else seeing such a big difference?
The difference is normal and you shouldn't look at it as if it was a loss, it's simply part of the game. There is some discrepancy like this with any source, you should only consider it a problem in case it is a large %.
Now, with clicked traffic, 20% would be way too much that's true. But the fact that you are using google analytics changes this a bit. According to my experience, GA always counts less than anything else I ever used
20% in this context is quite a good number actually. GA filters some traffic out, it takes longer to load so some users might close the site before it actually loads etc ...
Not sure what others have to say here, but this is my experience.
Add &utm_source={widget_id} to you campaign URL and analyse widget width big losses. 
Mb only some widgets send bad traffic. Block them and statistics will be normal