Short Answer: Snow is complicated and how solid it is depends substantially on the weather conditions of when if fell, and every day since it fell.
From the looks of that snow, as long as snow is on solid, simi-flat ground and the temp is below freezing, their isn't much risk of sideways collapse in enough quantity to hurt that dude. Snow forms layers as it falls which have fairly strong cohesion with itself, these layers then build upon each other (think plywood). With the right conditions you can keep huge walls of snow stable (ish) for months. On the flip side, these layers on the slopes of mountains are what make avalanches possible.
On the off chance it did collapse in enough quantity to cover him, it should be easy enough to get out of before running out of air. Its not like dirt of water, snow can hold more air, but eventually it can run out.
Read up on avalanche survival if you wish to know more on being buried alive by snow, or if you want to read about a horrible snowy way to die, read up on tree wells.
I vaguely remember reading that somewhere around 80%+ of volunteers in test situations could not save themselves in a tree well.
