Will the number of leads increase after launching a product on the Product Hunt?

Maybe. Some of the people I interviewed had offers from Angel investors and VCs, a lot of traffic and even some purchases. Of course, there were people with the opposite effect, but they didn't have some significant results. It is individual and you have to stand out. Make sure that your landing page and offer are really appealing, the onboarding process is smooth, and you can convince visitors and future users to pay.

I get significant traffic and backlinks from successful PH launches

It depends on your product and audience, but in general Product Hunt can drive a surge of early traffic and signups from tech-savvy early adopters. The key is having a compelling landing page, smooth onboarding, and ideally a free trial or freemium model to convert curious visitors into leads. Optimize your PH listing with eye-catching visuals, clear value props, and social proof. Engage with commenters to build buzz. Have email capture prominently displayed. With the right strategy, a successful PH launch can jumpstart your lead gen, but it's not guaranteed. As always, YMMV!