Harish, I may not be fully grasping your requirements, but I think the campaigns I outlined will do what you need.
After email 1, it will wait 7 days, then request another campaign that, as part of it's entrance criteria, will check if a link has been clicked and send only if not. You can also use smart lists as Josh described. So after 7 days, email 2 goes out if no click activity has happened.
Meanwhile you have a separate campaign that is listening for a click. If a click occurs, it cancels the other campaign by removing from flow, then waits 7 days from the date of the click to send the next email.
This is where you will achieve the staggered pacing you are looking for. The user action is driving this campaign and so it will wait for the time interval from a start date unique to each user's activity.
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