Lending is one way to increase your source of profit, it takes a lot of capital before you'd start earning a decent amount. You can check the forum's
lending section to get an idea of the situation. It's not the best option but it's better to have alternatives than sticking to one or two options.
If you want to step in the gambling world and at the same time take the smallest risk possible then i'd suggest investing in a casino's bankroll and join with the casino owners. Similar to lending you also need a lot of budget if you want a bigger profit since the distribution is based on the amount you're investing.
If that is about lending, I suggest that he lend his bitcoin in the exchange because I have had a good return in the past. Many exchanges right now offer a lending section to their members, which can be additional income to them. Although the interest is not too high because that will depend on the market situation, that is still an income without the trade.
But if he wants to use gambling to make money, we will not recommend gambling because gambling can make us lose money before making money. But if he can accept the risk of losing the money, we can not say anything because that is his money.