Wish I could help you out with an actual conversion but I don't use DaVinci - or any other - syrups in baking.

I would use half the amount of Splenda and just add the syrup to taste. You don't want to add too much liquid because it may make the cheesecake not set properly.

Cream cheese is heavy in calories but if it's your birthday, what the heck? Enjoy it!

Karen