If users skip or abandon the welcome survey, they have no way to return to it to complete it later (except by returning to the URL, which is not something we would expect any user to do). One idea we've had, and that @Urbanecm heard from a community member, is to allow users to "do this later", instead of skip, and then somehow surface the survey to them again. Perhaps this option is something that could be displayed on some kind of "newbie homepage".
It would be interesting to know why people want to "do this later". Are they rushing in something? Is the survey too much for them?
Allow people to do this later will, IMO, not be used: when you use an on-line service you never go back to a survey expect if it is displayed somewhere. Maybe open the survey in an other tab?