How long do I let my baby cry??

Rae

My baby is 6 mo and he cannot yet soothe himself to sleep. At first I let him cry 15mins, then 25mins, and he has gone as long as 45 mins with no signs of stopping!! I do go in every 10 mins to pat him and say “it’s ok” but I always end up rocking him to sleep, he just want me to hold him all night!