Way#1: Writers Start Asking You for Advice!
You know you've made it as an author, at least in the eyes of SOME people, when other writers start asking you for advice. I've actually had several writers approach me, mostly through email or on facebook or linked in. One gal asked for advice on getting children's books published. I didn't know at the time because I had never written one. Ironic enough a few months later I wrote one and a few months after that had a contract to publish it. But you know you're "making it" as an author when people see what you are doing, want to get there as well, and start asking you how you did it.
Way#2: People Give You Ideas
I remember reading somewhere a quote, I think from James Patterson or some other huge author like that that he does not accept ideas from people. The ideas he puts into his book are his and his alone and he has plenty of them. You know you are making it as an author when people try to give you ideas for your books. I feel like my head is full of ideas, but if someone has a better one and wants to GIVE it to me, I am honored to listen! The fact that someone thinks I'm a good enough writer to write an idea they have is a blessing to me. I cannot guarantee I will ever get to such ideas, but I am more than happy to listen to them! I have had an online friend give me a story idea and it's a good one!
I have yet to put out what I consider a REAL book. I have three romantic comedy novels and one children's book under contract that I feel WILL be truly published books. But suffice it to say, if you are earning royalties, you are making it as an author. However small they may be. I was astonished when I realized Amazon was making DEPOSITS to my account instead of taking money from me for stuff I buy like they usually do! It took me a while to figure out that "Someone Always Loved You" was actually catching on and I was starting to see small residuals. It is what drove me to start promoting the book!
Way#4: You love it
The best way to make it as an author is to truly love it. If you love writing and you get to do it as a career or even a hobby, you've made it! Enough said!