Looking only at the contributions of the surviving Jedi after Order 66, in what ways have they contributed to the Rebellion that would not have been possible without them?
Obi-Wan Kenobi and Yoda indirectly saved the whole galaxy from the Empire.
If it weren't for these two, pretty much nothing in Episode IV would have happened. Luke Skywalker and Leia Organa likely would have been discovered and killed not long after birth, Han Solo would never have joined the Rebel cause, the Death Star would not have been destroyed, et cetera…
Later on, were it not for Yoda's training, Luke wouldn't have been able to stand a chance against Darth Vader and the Emperor (and likely wouldn't even have attempted to confront them).
So the actions of Obi-Wan and Yoda, by protecting, training, and guiding Luke, directly contributed to Luke's ability to save the galaxy from Vader, Palpatine, and the rest of the Empire.