You might want to think of trust in two ways: Trust because of one area in a person’s life (he or she is a compulsive gambler, for example) or trust more generally (the person harms you in many ways and across time). Does your uncle have a particular weakness, such as we see in the gambling example? If so, then he would have to start building trust by small steps. Perhaps you are slowly seeing that he no longer asks for money from you, as an example. You need time to see that the particular actions are no longer hurtful. That may take a number of exchanges between the two of you before your trust begins to build. This could take weeks or even months.
If your uncle has general patterns of injustice which have hurt you, then this can take a lot longer. Try to look for instances of genuine change in him. Is he beginning to see what he has done? Is he remorseful by showing an inner sorrow for what he has done? Has he apologized or expressed regret to you? If he can give back something tangible to you, has he tried to do that? Look for what I call the Three R’s: remorse, repentance, and recompense. If you begin to see these, then your trust may begin to build.