I think it usually depends on the boy's decision whether to tell his right or not to lie but it is better to tell the truth because he is following religious lines. Even though he won $46k from sports betting, it's a really big amount his parents probably won't say anything about. Following his parents' orders, he can spend the money on other activities that will bring good things in his life. He can increase its value by doing business or investment. If he does good things, his parents will be happy. If he makes a wrong decision alone, he can suffer. It is expected that parents can guide him to the right decision.
It is better to tell the truth. It will free us from any form of shackles that can limit our freedom. The boy must tell his father about the incident and accept whatever the result is. Though I think money talks often time even though people are strictly religious people in front of people, we never know what lurks behind the scene. Aside from that, I believe the father will just give the son a proper reminding and with the thought of nothing negative happens, the father will be easy to the son. Besides I believe the son is old enough to stand for what he has done.