I am not familiar with this seller (probably because he is overseas), but if he is very highly respected, I would take his word for it. If you do not know anything about his reputation though, I would exercise caution.
Jungles are one of those very subtle morphs. There are some animals that are unquestionably jungles, and some that are nearly impossible to see in a picture. I think this is one of those.
I can see certain jungle influences in this animal, but without seeing it in person, I cannot say for sure if this animal is truly a jungle. If you are looking for a jungle specifically, I would try to find one that is a higher expression. But that's just my opinion.
As far as what the babies would look like, if this animal is actually a Jungle, than bred to a normal, he could produce both animals that look just like him or animals that have a really wild pattern. Jungle are like pied ball pythons in that sense - low expression can still produce higher expression offspring. This is why it is important to buy an animal like this from a highly reputable breeder - you can be assured that the snake is what the breeder says it is and the breeder can give you background and history on the snake and its parents so you have a better idea on what you can produce with it.
My initial thought is that if you have to ask here, the breeder isn't answering your question or you have reason to doubt the breeder. If that is the case, look elsewhere.