There is nothing on the TechNation side that seems to exclude older reference letters. However, I would like to believe that closer the letter is to the date of application, the better. Why not ask our endorsers to wait while you do whatever it is you need to do in the intervening period?
Is it OK if submit my articles to “Forbes online magazine” now and it is not considered a recent publication? And do you think “Forbes online magazine for senior IT professionals” is international online publication?
I don’t understand the first sentence. Secondly, what I think doesn’t matter. If you think it is a well read magazine, then go for it. If there is a public record of their circulation, you can screenshot and attach it for reference. If there is an analytics page showing how many readers have read your article, that might help too.
You mentioned Supporting letters, is this some extra letters from other people I know talking about me, etc. I am not clear about the Supporting letters and its content. I have searched and did not find much about it.
Please see My TechNation Application - September 2020 - #16 by Shreeniwas_Iyer on how I used supporting letters. These are extra letters outside of the reference letters. Content is entirely open-ended.
I assume I need to focus on how unique the things I have done in these companies.
Yes, you are thinking along the right lines.
I am worried that I will be rejected on the basis that my references/experience from consulting companies. Or should I focus on the value I will create from the company I will setup with unique products on the market after getting the GT visa?
Your reference letters are typically based on past work. A reference letter based on your vision is not a reference letter, but fiction. However, you can use your personal statement to paint a picture of how you plan to put your skills to work.
As for your worry about being rejected, I have already answered it in this previous comment - Am I eligible to apply? Please check - #5 by Shreeniwas_Iyer - I have nothing else to add to that comment.