This reply is a bit speculative because I don't have any experience on the non-mobile publishing side of things.
I doubt a PC release will have any impact on console sales, as the two markets are pretty isolated from one another. Lots of game developers play games on PCs and consoles, normal users typically don't.
However, a PC release might limit your ability to negotiate a beneficial exclusive (or timed exclusive) console release with one of the big manufacturers. If you have limited reach and marketing budgets, then exclusivity might be a good way to get some level of featuring and visibility in the online stores. It might be worth talking with your Xbox/Sony/Nintendo account managers before releasing on PC to make sure you're not missing out on any golden opportunities.