We've all but proven that the universe is infinite. Certainly, it is close enough to being infinite for any of our Earthly intents and purposes. We now also have evidence of other planets orbiting stars similar to our own sun, and methods have evens been proposed and explored of reaching them in less than one lifetime (which is almost unbelievably close, considering the size of the known universe). When taking into account the scale of what's out there, I find it impossible to doubt that there aren't countless other worlds with the right conditions to support life. Regardless of personal beliefs in the creation of life, I also find it difficult to imagine that our little speck in existince would be the only one destined to be graced with biological companions.
If there is no higher being who designed and built existence as we know it, it simply becomes a matter of odds whether or not other life exists. And the odds are in life's favor for the same reasons I have described above. Given, I'm not qualified to count the odds, but it is a well educated guess. Assuming there is a a god of one form or another who put us here, why just us and why here? I can't presume to put myself in a god's shoes and understand his intentions, but it seems pointless to me effortlessly create a single planet full of life and call it an eternity.
So to answer the question: Yes, there could be life on other planets. Since I can't imagine how it could be proven otherwise, we'll never know for sure whether there is until we actually find some.