If you have data showing a correlation of traction with some other variable then monitor and/or control that other variable.
As an example of a variable you can directly control: Price. Depends on the product, but in general, as one lowers the price of something, the demand (traction) will go up.
As an example of a variable you can't directly control, but can track: Engagement. If you have a Youtube channel and you notice more of your audience leaving comments, or clicking the thumbs up button, or watching the entire video from start to end, that's not only a sign that they are enjoying your content, and will be coming back for more, but also a indicates that more and more new customers will start being drawn to your channel either by word of mouth/email referrals, or by the Youtube algorithm advertising your video more since it sees increases engagement. So you would expect traction to increase.
In general, if you are collecting data from several layers of your "sales funnel" (Google it), as you see the % of users getting to lower and lower layers of the sales funnel go up, you can expect more and more traction. Both of the above examples would predict that future potential customers would go further and further down your sales funnel, thereby increasing traction.