Nutrition-wise, the answer is… no. Fruit jam does not replace a fruit. Indeed, the preparation of jam results from cooking a quantity of fruit to which is added a more or less equal quantity of sugar. As such, jam will be considered as any of the other sweet products.
In addition, and here is the essential part, a certain amount of fibers contained in that fruit as well as almost all of its vitamins disappear during the process of cooking. Hence, fruit and jam are not the same. On the other hand, and from an equivalence point of view, it is possible to occasionally substitute a fruit with a spoonful of jam but this will not bring us any nutritional benefit.