We have partnered with our integrated campaigns team to formalize roles and responsibilites and then we actually aim to share KPIs. I think it makes us stronger to feel like we are succeeding and failing together vs being able to say Product Marketing "succeeded" in a quarter where we didn't hit our pipeline target if that makes sense.
Ideally, it's a combination of the GM, product management and product marketing. The GM would set the overall business goals for the year or quarter including revenue. The PM often drives the product launch adoption and revenue goals for that product. PMM often builds the plan with the metrics to help back into those goals.
The important thing is that if you see a gap, make sure that someone is owning all of these goals, otherwise, it will be meaningless to have launch metrics.
My answer is predicated on product marketing owning the launch and deman gen having a component of the launch. Product marketing provides the target buyers, the target market segments, the value proposition, and translates launch goals into lead gen objectives. Lead gen has what they need to plan and execute.
This is challenging indeed and something I've had to deal with at every company I've worked for. What I've fund helps keep me and the business teams sain is to plan to launch features 14 days after the official planned released date. This makes product nervous most of the time, but most of the time they're also delayed so it all works out in the end.