process = new Process()
{
    StartInfo = new ProcessStartInfo(/*exe-path*/, arguments)
    {
        CreateNoWindow = true,
        WindowStyle = ProcessWindowStyle.Hidden,
    },
};

process.Start();
Thread.Sleep(1000);

 await Task.Run(() =>
            {
                while (!process.HasExited)
                {
                    var fileInfo = new FileInfo(restorePath);
                    var fileSize = BytesToString(fileInfo.Length);
                    Log(fileSize);

                    Thread.Sleep(3000);
                }
            });

string BytesToString(long byteCount)
{
    string[] suf = { "B", "KB", "MB", "GB", "TB", "PB", "EB" }; 
    if (byteCount == 0)
    {
        return "0" + suf[0];
    }
 
    long bytes = Math.Abs(byteCount);
    int place = Convert.ToInt32(Math.Floor(Math.Log(bytes, 1024)));
    double num = Math.Round(bytes / Math.Pow(1024, place), 1);
    return (Math.Sign(byteCount) * num).ToString() + " " + suf[place];
}