Hi Mathew, 

There is not a consistent rule when it comes to gmail's promotional folder. I would call Aweber to get their thoughts, as they will be able to pop the hood and better advice you on what is happening in your case.

The reality is though, that the promotional folder does impact things. Not horribly so, but it has a negative effect. One thing you can do is set up open and click tags in your funnel emails and then create a lookalike audience based on people who have opened past emails. This might help to clone people more likely to see and engage with your emails in the future.