The information we need is contained within the movies, but needs to be carefully examined and considered to get the answer. The relevant items from the movies are:
On entering Dagobah's atmosphere, Luke's X-wing immediately loses all sensors. Luke quickly engages the "Landing Cycle", and almost immediately it seems the fighter has crashed through the tree canopy, into a swamp, and come to rest without serious injury to the occupants.
On Luke exiting the fighter, we see that it has come to rest about half submerged.
In the prequel trilogy, we see several instances of craft entering atmospheres at speed exhibiting a re-entry glow
In episode IV our first image of an X-wing in flight tells us it has anti gravity vertical take off and landing capabilities.
Yoda's mastery of the force enables him to easily stop heavy large objects in mid air and return them in the opposite direction with great speed, as demonstrated in episodes II and III.
In episode VI when returning to Yoda's home, Luke does not experience any difficulties on final approach.
What can we tell from this? From the beginning. Luke must have entered the atmosphere at low speed, using the anti grav capability to prevent accelerating beyond the x wing's maximum atmospheric speed. we can tell this as there is no reentry glow as he enters the atmosphere. On losing sensors while still at significant altitude, Luke barely has time to lower the landing gear before splashing into the swamp. From this we can deduce that Yoda has used the force to grab the x wing in mid flight and pull it almost straight down to a soft landing near his home. we can safely assume that with this level of power and control, Yoda can ensure the x wing doesn't hit the water with enough speed to cause much damage. This is backed up by later references and events. When Yoda lifts the X wing from the swamp, the landing gear is down and undamaged, this would have been ripped off had the fighter been moving with any significant speed.
We also find out Yoda has been watching Luke grow up light years away, and is able to speak at will with Obi Wan, so he clearly had plenty of notice that Luke was coming, and would have been able to influence the course of Luke's approach to Dagobah to an extent so that major course alterations would not be necessary. Later Yoda uses removing the X wing from the swamp as a highly significant lesson in the true power and nature of the Force. We can take from this that Yoda planned for the x wing to land in the swamp in order to give this lesson, and also to remove Luke's access to some of the supplies onboard, in order that his training be more impactful due to Luke's having to endure adversity and discomfort.
Further information to support this can be taken from the apparent density of Dagobah's atmosphere, as seen in the humid misty swamp. this would indicate that Dagobah's atmosphere is roughly the same density at ground level as Earth, as these are similar to Eartly swamp conditions. Earth's atmosphere is about 60 miles high, so given the short time the X wing takes to get from orbit to ground, without severe damage or reentry glow, we can deduce that it did not enter at high forward speed, and having traversed 60 miles of height in no more that a few minutes, there must have been intelligent control of this descent. We can also deduce that this intelligent control was not by the X Wing's flight systems, as sensors were down, and had they been able to detect the ground enough to slow descent to a safe speed, it would not have crashed through trees and landed in the swamp with the speed that it did.