I'd suggest 1-2 hours at just reading what's allowed and what isn't on the AdSense TOS page... It'll help in the long run. P.S: Big NO for gambling sites.
You can`t put adsense to any illegal material containing page. Gambling is illegal content, so answer is no. And for the sites that has adsense at gambling pages. It is taking a risk, you can go to jungle and have a fight with a lion with your punch but winner will be always lion
I've seen adsense on a few gambling blogs. However, these blogs had no advertising for gambling websites, just articles about gambling. As always, if you are unsure it's best to email your site url to the Adsense team and get official approval from them, not forum members.
As suggested, its not ok, its always worth a good and regular read through their TOS, i know it can look overwhelming but i feel its worth reading it regularly. Print out their TOS and read it when you have a moment to yourself, for your own safety.
Why would you choose AdSense for gambling blog though? Better though use free referral programs from cosino/betting/poker sites. More revenue, and fully allowed. Google says no for gambling/adult. That is clear.
checkout bidvertiser if you want to display ads on a gambling site... i am pretty sure they allow it because they have tons of gambling related ads showing all the time