Furthermore,Can open source contributions help you land a consulting gig.
I have however hired many people over the years, so I will comment from that point of view.
The key word in your question is Help. just having done some open source isn't some sort of magic bullet. But it does open the door to discussing what you did, how it helped you, what you learned and so on.
In other words it supplements your "experience" factor. Especially for folk starting out it's an obvious solution to the "but how do I get experience if everyone only hires experience?" question.
Put another way, given unemployment you can either do nothing, or find a way to add value to something for free.
When it comes to hiring - for a small shop - the willingness to add real value, and the demonstrated ability to do so, goes a long way to getting hired.
But it's only one of several factors, not the only factor.