An exemplar of the Viking heading East is Harald Hardrada. Beginning life in Norway, he was forced into exile following a failed uprising against Cnut the Great, King of the Danes who ruled Norway. He made his way east, to the lands called the Russ (Russia) and turned south to Kiev. Eventually, he came into the service of the Byzantine Empire.

Harald Hardrada fought in many battles in Asia Minor, the Levant and Eastern Mediterranean. 'India' would have been known to the peoples he was fighting with and against, he may have seen their goods in a marketplace or overheard traders discuss their routes there in port. While there is no evidence I know of to support that Harald Hardrada had such knowledge, it is not a far fetched assumption.

But Hardrada's fate lay in the west. Eventually, he returned to Norway, claimed a kingdom there, fought the Danes quite a bit and eventually tried to capture the English throne. He died in the effort. William the Conqueror has Harald Hardrada to thank for wearing out Harold Godwinson's troops at Stamford Bridge, only two weeks prior to Hastings and the Norman triumph.

So there is one example of a well traveled Viking (1015-1066 C.E.) who plausibly had second-hand knowledge of what we refer to as India today. He made it fairly far east, and was able to return home again and possibly tell other Vikings about it.

Hope that helps

I'd like to add the Helgö treasure to what has been said previously. It is a hoard found in Helgö, which was a major commercial port in Sweden at the time.

In the hoard were a ladle from coptic egypt, a bishop's crozier from Ireland, arabic coins... and a small bronze statue of a buddha. The buddha statue is usually attributed to artisans from today's India or Pakistan around the sixth century AD.

This is not to say that Helgö people had been to India though, as such objects could have been (and frequently were) passed from hand to hand on the trade routes. But it shows that the guys liked "exotica" and knew there were other peoples, different from the people they were directly trading with, further on the Russian route.

The treasure is displayed at the Swedish History Museum in Stockholm but I could just find a page about the bishop's crozier with a mention of the buddha statue on their site.