I don't think so, In fact, it benefits both of them since p*rn sites has a lot of users around the world it will promote the cryptocurrency to a huge amount of users at the same time. If you are familiar with Verge (XVG) they are already partnered with Pornhub, Also TRON and it has no negative effects on the platform.

Of course it will have a negative impact and indeed, sometimes I find out from those who accept payments using bitcoin and some of them even accept some other crypto too. This adoption continues to grow but when greater adoption of something negative like this, then of course it will have a bad impact for bitcoin itself because it grows in a place where even many countries forbid accessing porn sites.

I don't think it will affect Bitcoin negatively because it's still a form of adoption. We all know that there are lots of porn site users  and it simply means that more users would tend to use Bitcoin for their convenience. The porn industry has been using Bitcoin as a mode of payment for years and it didn't affect crypto negatively but rather benefit both parties.

When Verge made a partnership with PornHub, there are no changes in their coin but did a "Buy the rumor, Sell the news" thing. Now I don't hear anything about Verge anymore and correct me if I'm wrong but PornHub doesn't accept Verge anymore.

Now with the negative effects, I don't see any negative on it but rather a positive because it is an additional advertisement for Bitcoin and crypto as a whole

According to this article. LINK

–In 2017 alone, Pornhub got 28.5 BILLION visits. That’s almost 1,000 visits a second, or 78.1 million a day—way more than the population of the entire United Kingdom. That number has since jumped to 33.5 billion site visits in 2018.

–In 2016, 91,980,225,000 videos were watched on Pornhub. In 2018, that number jumped to more than 109,012,068,000. That’s over 14 videos watched for every person on the entire planet.

-Also, more than 5,517,748,800 hours of porn were watched on the site in just 2018. That’s equal to 629,880 years of content consumed in 1 year, on one porn site.

You can imagine how many people are watching daily and this is a huge advertisement for Bitcoin since porn sites can attract so much traffic in a day.

A good example how bitcoin works in terms of providing privacy to any person who doesn't wants to reveal himself while watching porn. Using hardware wallet he can simply send bitcoin to the pornsite that he wanted to use and discreetly do his business without any restrictions.
Like what those post above mentioned, bitcoin are already existing from porn industries not that much effects both negatively or positive.

I believe porn site will only give the crypto currency a favorable effect because almost 36% of all the internet video downloads was said to be porn-related and as at of the year 2018 statistic shows that 7 million new porn videos were created while billion searches/watch were made per every hour. This is the reason why some musical and private companies advertised their product through porn sites.
Therefore, if porn site integrate bitcoin payment then will just see some positive news and more price pump.

With the percentage reaching 36% it means pornographic content is one way to meet the biological needs of most people. And biological needs are something that is privacy and some negative views related to pornographic content, the existence of alternative payments using bitcoin can be a very good solution for those who want their identity to be obscured, iykwim. So in my opinion, this actually makes itcoin better known and felt by people in "sensitive" niches.

It's a business that's and they need to earn with it but what you paid is quality videos but if you can't pay they also offering a free with is still good since they have hd covered.

But in using it on subscriptions well yes it can create a impact since it will give demand to the bitcoins itself but I don't think it's huge since not all people willing to pay some bucks to see those videos around.

The adoption of bitcoin for payment on the Porn site will not have a negative impact on bitcoin. Although many porn sites are in about by some circles, these sites have millions and even billions of customers throughout the world. This will make bitcoin increasingly sought after and many investors are interested in bitcoin.

Just a small example with XVG coins in collaboration with pornh*b that made XVG increasingly known and experienced a surge of increase that is fantastic.

Negative and positive effects do always occur, but we must look more dominant towards what is more positive or negative.