Hello, been here just over a year now with my webcomic!
Generally in terms of what's going to get you seen more is probably having a substancial backlog of chapters and having a couple of people read through the entire thing while liking. That's happened to me a couple of times and I post page-a-week so when two kind souls read through all my pages and liked every one it boosted my comic a lot. I get that it can be frustrating to hear "you need to have people reading to get people reading" but it does only take a couple of people coming across your work by chance once you've built up some story to help you 
Subs alone does basically nothing from what I can tell, if they don't read through and like/comment it's more or less an empty number, so stuff like sub 4 sub is usually pointless if it's just subbing and not reading.
In terms of motivation I try to be as detached from the numbers as possible. My motivation comes from being able to tell the story I want to tell, to get to draw the scenes I've been itching to draw for years. That's something I can control and I know that when I don't want to do that anymore it's time to move on to something else. Motivation can come and go but I've never not wanted to tell this story so it's a nice constant in my life I can always count on to keep me going. So yeah the numbers on tapas don't really factor into my motivation, but this is a learned behaviour that I had to teach myself for my mental health.
The one thing that does boost my motivation a lot though is having insightful comments. I'm lucky enough to have 2 regular commenters and a handful of semi-regular commenters who are always a joy to hear from. Not having those comments won't hurt me but having them is a definite boon to working hard on the little things.
One of those commenters actually followed me from Wattpad so despite my better judgement I feel a few people would follow me onto other platforms if it were convenient for them, but it would be nowhere near the current numbers on tapas. I'm just glad to have anyone reading you know?