From the looks of the first trailers for Wonder Woman, it looks like there's no shortage of action and amusement in the latest DCEU film. What the previews also do, interestingly, is show that this particular origin story is set close to the turn of the century — World War I, to be precise. This raises the question of whether Wonder Woman is immortal— because seriously, seeing that Batman v Superman, where she had a cameo, was set in the present day, just how long has Diana (aka Wonder Woman) been alive?!
A 2015 article from Cinemablend suggests that Diana's age varies depending on what medium she's in and is dependent on the storyline. For example, the current DCEU implies that Diana is over 100 years old, because when we meet her in Batman v. Superman, she makes reference to why she left society behind before returning back to the fold in 2016. Too much bloodshed among mortals left her disillusioned, but the cinematic universe is now pulling her all the way back in for Justice League.
Cinemablend cites other examples of Diana's varying age, too. This includes the 1970s TV show starring Lynda Carter, where her age is implied to be hundreds of years old. In one DC Comics storyline, the New 52, Diana's age might be 23, as the site purports. Basically, your guess is as good as mine when it comes to deducing Diana's true age. This in turn strengthens that possibility that the hero may have an above-average life expectancy, if not be fully immortal.
This idea of, at minimum, an extended lifespan could be supported by Diana's own acknowledgement that she was created by Zeus, top dog of the Greek gods, as she tells Steve Trevor in the first Wonder Woman trailer. That immortal and godly parentage could mean that Diana inherited some of that immortality to help her live longer.
It will be interesting to see if Wonder Woman acknowledges Diana's age or if it will tiptoe around the idea and merely drop hints or implications. If Diana is indeed immortal, then this could be the first of many, many films where she appears.