We get a lot of tourists on our farm as we span Hadrian's Wall at one of the venues.
We have all sorts of gates and there will be the odd accident with any of them!
But generally the sheep do not get through new / well-maintained kissing gates, no. We do have one old and tired one that they do use
but on the whole they work. For the most part our fields have a kissing gate for walkers next to a field gate for us - and we do find that the walkers will on the whole use the kissing gate and not open the field gate, risking then not shutting it properly.
All of our kissing gates are the spring-loaded type, and although the sheep
could push through them from the shutting side, they generally don't.