Need some questions answered for my lil cousin

[unit321]

My cousin is wanting to start weightlifting and wanted some questions answered. Rather than send him to bodybuilding.com, i asked here first. He is about 6 feet tall and weighs 120 lbs. He wants to get to about 190 lbs. He has read something about 'noob gains' and doesn't know how much he can expect this to be since he is underweight. Like apparently, you get gains faster at the beginning of weightlifting and those are noob gains. But he feels like his will be bigger bc he is not at the weight level he is supposed to be at. Does anyone here know about this shyt and also about how long does it take to get about 70 lbs of relatively lean muscle mass? I am bigger than his goal weight but i was never that small to begin with, so i can't answer his questions.

Well, everyone is different. But, everyone peaks out after noob gains are made. What that peak is when you can't get beyond a certain plateau. He may have been able to add 10 lbs. a week to his bench press. But there's going to be a time, when that goes down to 5 lbs. a week, and then it's going to plateau to 0 lbs. a week.
Without seeing his body type, he may gain 30 lbs., he may just gain 10 lbs. Who knows. Just start.