No amount of signatures is going to get a sequel made. The first one was a massive flop at the box office making only 35m out of a 50m budget. And that's not even counting the money they pumped into marketing. I thought the movie was fine, but it's not getting a sequel.
There's more revenue streams and indicators for success to a film than just box office sales. The marketing budget was not that large, and if DVD sales are good, streaming demand and cable viewership is high, and word of mouth is spreading, a studio could easily decide that a 2nd one could make money and with a built in fan base there is much less of a risk financially than trying a new movie. It is very possible to get a sequel, even if it's box office receipts were lower than their production cost.