Answers from atheists will vary on this point. Some will say that "anything is possible", so the answer to this question may be a simple "yes" from those people.

Possibility is something that needs to be argued in itself. We don't know whether it's possible for a god to exist or not. If we can't argue that something is impossible that doesn't mean that we assume it's possible by default.

Of course, it depends on the definition of a particular god, such as whether it can violate the laws of logic... but if we're talking about a being outside this universe, creating this universe, that may not violate logic, but we also don't know whether it's possible.

So the answer to the question is "maybe"

Note: The original answer for this response was "of course". The author's understanding of the topic has since evolved.