Regardless of new world origin or old world one, we don't have any physical [contemporary] evidence of the historicity of Leif, as is mostly the case with the Icelanders in the Age around 1000. His father Erik the Red, 'A man called Eiríkr the Red from Breiðafjörðr' and his voyage [and naming] to Greenland, however, had already appeared in the Book of the Icelanders (Íslendingabók), the oldest historical writing from medieval Iceland in the early 12th century (before 1133). Thus, the historicity of the related figure of Leif is at least better documented than most of the Icelanders. While the Book of the Icelanders is also the second oldest accounts mentioning Vínland (the oldest is actually written in Germany), though, this historical account neither mention the name of his son, Leif, nor associate Vínland with any known figures in later traditions like famous Vinland Sagas, the Saga of the Greenlanders (Grönlendinga saga) and the Saga of the Erik the Red (Eiríks saga rauða). Leif played an important role in the episode relating to Vinland first in 13th century saga traditions.
We don't have any archaeological evidence that enabled the exact identity of a group of the Norse people who occupied L'Anse aux Meadows, hither to the only known Norse [temporary] settlement in New World and the island of Newfoundland, Canada. Researchers do not agree whether Vínland depicted in later traditions is actually this site.
Not to discourage further discussion, but this previous answer to a similar question discusses L'Anse Aux Meadows in Newfoundland, which may answer your immediate question.