Scholars cannot prove that there is a real relationship between Moses and Ramesses II because it is unclear if Ramesses II is the pharaoh mentioned in conjunction with Moses in the Bible. In fact, scholars even squabble over whether there were two pharaohs or just one during the time Moses spent in Egypt.
If Ramesses II was one of the pharaohs who reigned during the Hebrew exodus in Egypt, then his daughter was the one who picked Moses out of the river and adopted him, making Moses part of the royal family. Some theories say that Seti I, who was the predecessor of Ramesses II, was the father of the woman who adopted Moses, but this then makes Ramesses II the second pharaoh during Moses' time who died in the Red Sea, and historical accounts say that Ramesses II died in his home.
Another problem is that scholars cannot find a specific mention of a man named Moses in ancient Egyptian history. However, there is a working theory that the name Moses is derived from Thutmose, who also happened to be the mysterious son of pharaoh Amenhotep III who disappeared into history without a trace. Yet another theory says that Thutmosis III was the pharaoh during Hebrew exodus. Either way, there is no clear relationship between Moses and Ramesses II.