Unfortunately, the answer isn´t a simple one.
The idea of the battle-slain going to Valhalla, the Warrior´s Paradise, is found in a 13´th century text called the Edda, nowadays called the Prose Edda, written by one Snorri Sturlson. He was an Icelandic Skald who was the author of a few works, including the Heimskringla (Chronicles of the Kings of Norway), which contains the pseudo-historical-mythic Yngling Saga. The Prose Edda was a collection of various stories from what we now call Norse Mythology, alongside instructions for how to write poetry. He was also, however, a Christian, and by many accounts, a real nasty piece of rat-work, who seemed to play a significant role in Iceland losing independence and becoming part of the Norwegian Kingdom.
Outside of Sturlson´s work, Valhalla does get mentioned, even in the more authoritative works compiled into what´s called the Poetic Edda, which contains poetry that might actually have been written by Viking-age pre-Christian Icelanders... and keep in mind that those vikings weren´t raiding a whole lot. They were explorers, not pirates. In these contexts, it´s difficult to say exactly what Valhalla is; could easily be just another word for Hel or Niflheim, that is, the place you go when you die. The word "val" in "Valhalla" translates to "wæl" in Old English (æ is pronounced as in modern English father), and roughly means "slain/slaughtered masses". Valhalla could easily have been a reference to any place where a mass slaughter took place, whether in a battle-context or not, and I tend to think of a wælhall as akin to a mosoleum or memorial hall.
And these works we do have weren´t being written by viking raiders, who, far as I know, left us no written records beyond a few rune-carvings on stones and tools here and there. So, when it comes to what the raiders believed, whether they had such a strong warrior cult and believed in the Warrior´s Paradise, I don´t think we really know for sure at this point. Seeing as the raiders were typically going after monasteries, and thus weren´t really risking life and limb for a good fight but actually slaughtering, raping, and pillaging people who didn´t have much means of fighting back, I kinda doubt that dying in "battle" would have been much of a concern.