Hi
In my experience a corporate or product blog is always useful because it provides content for users and for Ecommerce websites it can be a place to answer users inquieries or to announce events, or to keep in touch with bloggers ans the community, etc
But you must have a content plan and try to post new posts on a regular basis. Don't put the focus on Google but on users. You can easily capture new visitors if your content is relevant.
In my experience (Ecommerce websites) blog traffic represents 5 to 12% of global visits with good engagement rate.
Hope this will help you and your team