It's worth noting, IRT: Cap One, that the email you get from Capital One regarding Credit Steps is just the minimum they'll actually hand you. I've seen people get anywhere from what their email said to multiple times their credit limit. I'm pretty sure it has to do with both your profile and your internal history with Cap One, though -- I have never prequalified for anything with them but I got a QS1 10 months after I got a secured card with them (that also went through Credit Steps and got that $300 increase, but that's really neither here nor there).
When I got my QS1 I had a SL of $500 and was told via email that after I complete Credit Steps, I'd get a $250 increase. I have the email still. When I finished Credit Steps, they actually gave me a $500 increase. Even though it wasn't multiple thousands, I was pretty thrilled that they nearly doubled my limit (I got a luv button $100 sometime before I completed Credit Steps).