Could you elaborate on "can the iPad Mini beat the Google Nexus 7"? Are you referring to market share? Hardware spec? Benchmarking?
In terms of software features i think it'd be safe to assume it will run on IOS6, so software features will be most likely the same as with other IOS devices out there. Same story for general responsiveness, it's going to be running either an A5, A6 or a variant type (such as the A5x in the 3rd gen iPad) No reason to assume general performance will be any less than other current IOS devices (in real world use)
When it comes to market share, even if the Google Nexus 7 turns out to be much better value for money and a better piece of hardware, it's got Apples massive market presence to deal with and i think it's easy to underestimate that. Apple have managed to embed the iPad into modern culture in a way that its already synonymous amongst the masses as being a new, elegant style of computing device. When i say the "masses" I'm not referring to the IT/Tech folk like you and me, i'm talking about the other 80% of the world who doesn't care how the stuff works as long as it does what it does as simply as possible. To provide an example of what i mean: i do IT support for the government and look after politicians who are mostly elderly and have never used a computer before, most of them couldn't even turn one on without help. However, they'll happily all try an iPad as they hear its great. if given another tablet they actually call it an "iPad" even if its actually Android or Windows 7 "This isn't a proper iPad is it?" is a quote i've heard more than once. I actually hear about my friends 3-8 year olds wanting iPads for Christmas too, they never seem to ask for a Nexus 7 or other tablet devices. As good as the competition gets, its got a long way to go to get the sort of attention Apple gets from the public at large.