well. it's not simple gaussian.
I'm guessing it's photoshop, otherwise what would the point be. It's not a terribly good example, as the background is blurred by the pool of water, making fake blur easier to be convincing. I am also not sure if I am seeing any depth of field, or if there is it's not quite scene accurate.
If it is PS, then it's doing a good job at not-so-perfect bokeh, as illustrated in the plants in the middle ground.