There is a small distinction between the two questions.
Please consider the following exchange:
- No he visto a Juan en la fiesta
- ¿Es que tienes ganas de verlo?
Which translates to:
- I haven't seen Juan at this party
- Could it be that you want to see him?
Versus the next one:
- No he visto a Juan en la fiesta
- ¿Tienes ganas de verlo?
Which translates to:
- I haven't seen Juan at this party
- Do you want to see him?
As you can see, there is a small tonal difference. The first one could lead to a playful teasing conversation "Since when do you like Juan?" while the second is more neutral.
Here are a few phrases equivalent to "¿Es que tienes ganas de verlo?" in Spanish:
- ¿Será que tienes ganas de verlo?
- ¿Podría ser que tienes ganas de verlo?
- ¿Acaso tienes ganas de verlo? (As mentioned by Paco)
- ¿Acaso es que tienes ganas de verlo?
- ¿Acaso será que tienes ganas de verlo?
- ¿Acaso podría ser que tienes ganas de verlo?
As you can see "Acaso" is somewhat optional.
Note that this is from observation of Latin American usage of Spanish, so Paco's point is valid in Latin American countries, as well.