ThredUp, the online thrift retailer, is being valued at $1.3 billion in advance of its initial public offering slated for for this year. The company, which sells clothing for women and kids, saw its revenues jump 14 percent last year to $186 million, even as it lost $48 million. ThredUp reported having 1.2 million active buyers on the site, a 24 percent increase over 2019.